HK1092954B - Method of constructing a unitary amorphous metal component for an electric machine - Google Patents

Description

Method of constructing a unitary amorphous metal component for an electric machine

Background

1. Field of the invention

The present invention relates to a magnetic component for an electric machine such as an electric motor; and more particularly to a method of constructing a low core loss unitary amorphous metal component, such as a rotor or stator for a high efficiency axial flux electric motor.

2. Introduction to related Art

Rotating electrical machines almost always comprise at least two magnetic components, a stationary component, i.e. a stator, and a rotor arranged to be rotatable relative to the stator about a determined axis of rotation. Such rotating electrical machines allow exchanging energy between electrical and mechanical forms. More generally, electric motors are provided with a source of electrical energy from a battery or grid that can be converted into useful mechanical work. On the other hand, the generator absorbs the applied mechanical work and converts it into electrical energy that can be used to operate other equipment. In many cases, the same structure can be used to perform both functions, depending on how the motors are electrically and mechanically connected.

Most rotating electrical machines operate electromagnetically. In such machines, the rotor and stator typically comprise ferromagnetic material. These components are used to generate or direct a flux distribution pattern that varies in time or space, or both. The energy conversion between the electrical and mechanical forms is carried out according to well-known electromagnetic principles, in particular faraday's law and ampere's law. In an electromagnetic machine, at least one of the rotor and the stator is constructed from soft ferromagnetic material and provided with windings arranged to conduct electric current and generate a magnetic field. Depending on the type of motor, the other component comprises a permanent (hard) magnetic material or a soft magnetic material that can be excited by the energized windings or by induction. The most commonly used soft magnetic materials are low carbon steels and silicon-containing electrical steels, both of which are crystalline metallic materials.

The rotor and stator in an electric machine are separated by a small gap that is either (i) radial, i.e., generally perpendicular to the axis of rotation of the rotor, or (ii) axial, i.e., generally parallel to the axis of rotation and spaced apart by a distance. In an electromagnetic type machine, lines of magnetic flux connect the rotor and stator by traversing the gap. Electromagnetic machines can therefore be broadly divided into radial or axial flux designs. The corresponding terms "radial spacing" and "axial spacing" are also used in the field of electric motors.

Radial flux machines are currently the most common. The rotors and stators used in such motors are typically constructed from multiple laminations of electrical steel that are stamped or cut to the same shape, stacked in alignment and laminated to provide a component having the desired shape and size and sufficient mechanical integrity to maintain the construction during the manufacture and operation of the motor.

One common design for a stator is generally cylindrical and includes a plurality of stacked laminations of non-oriented electrical steel. Each lamination has the annular shape of a circular washer with a plurality of "teeth" which form the poles of the stator. The teeth project from the inner diameter of the laminated laminations and point toward the center of the opening of the cylindrical stator. Each lamination is typically formed by stamping mechanically softer, non-oriented electrical steel into the desired shape. The formed laminations are then stacked in alignment and bonded together to form the stator. During operation, the stator is periodically magnetized by a magnetic field generated by current flow in windings around the teeth of the stator. Such magnetization is required to drive the motor; however, inevitable losses are caused by hysteresis. These losses result in an overall reduction in motor efficiency.

The frequency at which axial flux designs are used is much less, due in part to the lack of suitable means for constructing components having the requisite electromagnetic performance and sufficient mechanical integrity. Certain publications have proposed the design of axial flux motors, including those disclosed in U.S. patent 4394597 to Mas and U.S. patent 5731649 to Caamano. These teachings also propose magnetic components that employ amorphous metals.

Although amorphous metals may provide superior magnetic properties, including lower hysteresis losses than non-oriented electrical steels, they are generally considered unsuitable for use in electric motors due to certain physical characteristics and the resulting impediments to conventional processing techniques. For example, amorphous metals are thinner and harder than non-oriented steel. Thus, the conventional cutting and stamping processes result in faster wear of the manufacturing tools and dies. The resulting increase in mold and manufacturing costs makes it commercially impractical to manufacture amorphous metal components, such as rotors and stators, using conventional techniques. The thinner nature of amorphous metal also results in an increased number of laminations for a given stack height component, which further increases its overall manufacturing cost.

Amorphous metal is generally provided in the form of a thin continuous strip having a uniform bandwidth. However, amorphous metal is a very hard material, making it difficult to cut and shape easily. Once annealed to achieve optimal magnetic performance, it becomes very brittle, making it difficult and expensive to construct amorphous metal magnetic components using conventional means. The brittleness of amorphous metal also leads to durability concerns for electric motors or generators that employ amorphous metal magnetic components. The magnetic stator is subject to extremely high magnetic forces, which vary at very high frequencies. These magnetic forces can create very large stresses on the stator material and can damage the amorphous metal magnetic stator. The rotor is also subjected to mechanical forces due to normal rotation and due to rotational acceleration when the motor is energized or de-energized and when sudden changes in load may occur.

Another problem with amorphous metal magnetic components is that the permeability of amorphous metal material also decreases when it is subjected to physical stress. This reduction in permeability is significant, depending on the strength of the stress on the amorphous metal material, as described in U.S. patent 5731649. When an amorphous metal magnetic stator is stressed, its efficiency in directing or focusing the magnetic flux is reduced, resulting in higher magnetic losses, reduced efficiency, increased heat production, and reduced power. This phenomenon, known as magnetostriction, may be caused by stresses resulting from magnetic forces during operation of the motor or generator, mechanical stresses resulting from mechanically clamping or bonding or fixing the magnetic stator in place, or internal stresses resulting from thermal expansion and/or expansion due to magnetic saturation of the amorphous metal material.

A limited number of non-conventional approaches have been proposed to construct amorphous metal components. For example, Frischmann, U.S. Pat. No. 4197146, discloses a stator fabricated from molded dense amorphous metal sheet. Although this method allows complex stator shapes to be formed, the structure contains a large number of air gaps between the discrete sheet-like particles of amorphous metal. This structure greatly increases the reluctance of the magnetic circuit and thus the current required to operate the motor.

To avoid stress-induced degradation of magnetic properties, U.S. patent 5731649 discloses constructing amorphous metal motor components from a plurality of stacked or wound amorphous metal portions and mounting these portions in a dielectric housing. This patent 5731649 also discloses forming an amorphous metal core by rolling amorphous metal into a laminated winding using epoxy, which disadvantageously limits the thermal and magnetic saturation expansion of the material windings, resulting in higher internal stresses and magnetostriction, thereby reducing the efficiency of a motor or generator incorporating such a core.

The method disclosed in german patents DE 2805435 and DE 2805438 divides the stator into wound pieces and pole pieces. Non-magnetic material is inserted into the joint between the wound piece and the pole piece, which increases the effective gap and thus the reluctance of the magnetic circuit and the current required to operate the motor. The layers of material making up the pole pieces are oriented with their planes perpendicular to the plane of the layers in the backwound iron piece. This configuration further increases the reluctance of the stator because the adjacent layers of the wound pieces and pole pieces only make point contact at the seam between their respective surfaces, rather than along an entire line segment. In addition, the method proposes that the laminations in the wound pieces can be joined by welding. The use of a heat intensive process such as welding to join the amorphous metal laminations will recrystallize the amorphous metal at and around the joint. Even small amounts of recrystallized amorphous metal typically increase the magnetic losses within the stator to unacceptable levels.

In addition, amorphous metals have far lower anisotropy energy than other conventional soft magnetic materials, including common electrical steels. As a result, stress levels that do not adversely affect the magnetic properties of these conventional metals will have a severe impact on important magnetic properties of the motor components, such as permeability and core loss. To this end, U.S. patent 5731649 discloses a magnetic component comprising a plurality of amorphous metal segments carefully mounted or contained in a dielectric housing without being bonded using an adhesive.

Despite the advances represented by the above disclosures, there remains a need in the art for methods of constructing improved amorphous metal motor components that exhibit a combination of superior magnetic and physical properties required for high speed, high efficiency electric machines, particularly axial flux designs. There is also a need for a construction method that efficiently utilizes amorphous metal and allows for mass production of axial flux motors and components used therein.

Summary of The Invention

The present invention provides a method of constructing a single-piece or unitary amorphous metal magnetic component for a high efficiency axial flux electric motor. The component may be a rotor or a stator. In one embodiment, the component comprises a cylinder of annular cross-section having cylindrical inner and outer surfaces, two opposing annular faces, an axial thickness separating the annular faces, and a plurality of radial slots in at least one of the annular faces for receiving electrical windings. The cylinder is formed from spirally wound amorphous metal strip. The layers are preferably electrically insulated from each other to reduce eddy current losses. The unitary construction eliminates all magnetic gaps within the component, thereby providing a closed loop through which magnetic flux can flow. The term "motor" as used herein generally refers to various types of rotating electric motors, including generators and regenerative motors that may be selectively operated as generators, in addition to conventional motors.

A unitary amorphous metal magnetic motor component constructed in accordance with one aspect of the present invention exhibits very low core loss under periodic excitation. As a result, the magnetic component can operate at frequencies from dc up to 20000 hz. It exhibits improved operating characteristics over magnetic components made of conventional silicon steel in the same frequency range. The operability of the component at high frequencies allows it to be used to manufacture motors that operate at higher speeds and at higher efficiencies than is the case with conventional components. Constructed in accordance with the invention and excited to a peak induction level "B" at an excitation frequency "f_maxThe magnetic component of "may have an iron loss less than" L "at room temperature, where L is represented by the formula L0.0074 f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4Core loss, excitation frequency and peak induction levels are given in watts/kilogram, hertz and tesla, respectively. The magnetic component may have (i) a frequency of about 60 Hz and (ii) a magnetic flux density of aboutAn amorphous metal material having a core loss of about 1 watt/kg or less when operated at a flux density of 1.4 tesla (T); (ii) an amorphous metal material having a core loss of about 12 watts per kilogram or less when operated at a frequency of about 1000 hertz and a flux density of about 1.0T; or (iii) an amorphous metal material having a core loss of equal to or less than about 70 watts per kilogram when operated at a frequency of about 20000 hertz and a flux density of about 0.30T.

The bulk amorphous metal magnetic component of the present invention may be fabricated using a variety of ferromagnetic amorphous metal alloys. Generally, the amorphous metal consists essentially of a metal having the formula M_70-85Y_{5- 20}Z_0-20Wherein "M" is at least one of iron, nickel, and cobalt, "Y" is at least one of boron, carbon, and phosphorus, "Z" is at least one of silicon, aluminum, and germanium; with the proviso that (i) up to ten percent (10%) atomic percent of component "M" may be replaced by at least one of the metallic species titanium, vanadium, chromium, manganese, copper, zirconium, niobium, molybdenum, tantalum, hafnium, silver, gold, palladium, platinum and tungsten, (ii) up to ten percent (10%) atomic percent of component (Y + Z) may be replaced by at least one of the non-metallic species indium, tin, antimony and lead; (iii) up to about one percent (1%) atomic percent of component (M + Y + Z) may be incidental impurities.

The present invention also provides a method for constructing a low core loss, unitary amorphous metal motor component. In general, the method comprises the steps of: (i) helically winding ferromagnetic amorphous metal strip or ribbon material to form a wound cylinder of annular cross-section having cylindrical inner and outer surfaces and two opposed annular faces separated by an axial thickness; (ii) carrying out heat treatment on the cylinder; (iii) bonding each layer of the wound cylinder to the layer adjacent thereto with an adhesive; and (iv) shaping the component by cutting a plurality of grooves into at least one of the annular faces, the grooves extending generally radially between the inner and outer surfaces and having a depth less than the axial thickness. The adhesive bonding is preferably carried out by impregnation. Alternatively, a finishing step (v) may be performed, including coating the component to obtain a suitable surface finish. The heat treatment step includes one or more heat treatments to alter the mechanical or magnetic properties of the amorphous metal feedstock. This optional heat treatment facilitates the machining operation and improves the magnetic properties of the part. Steps (i) to (v) may be performed in a variety of orders and using a variety of techniques including those described below.

The present invention also relates to a unitary amorphous metal component constructed according to the above method. In particular, a unitary amorphous metal magnetic motor component constructed in accordance with the present invention exhibits low core loss and is suitable for use as a stator in a high efficiency, axial flux electric machine.

The invention also provides an axial flux electric motor comprising an electric motor, generator or regenerative motor incorporating the above-described unitary amorphous metal magnetic component. In one aspect of the invention, the motor is of the induction type and incorporates at least one unitary amorphous metal stator component. The induction motor may optionally further comprise a unitary amorphous metal rotor. In another aspect, the motor is a brushless, axial flux, permanent magnet dc motor having a generally cylindrical, unitary amorphous metal stator including a plurality of tooth-shaped pole segments projecting axially from and integral with a generally annular back iron region. The motor further comprises a disc-shaped rotor having at least one permanent magnet portion with at least one pair of opposite magnetic poles, and bearing members for rotatably supporting the rotor and the stator in a predetermined position relative to each other. The poles of the rotor are located on the disc surface and generate magnetic flux in a direction substantially perpendicular thereto.

Advantages provided by the present invention include simplified manufacturing during construction of the unitary amorphous metal component, reduced manufacturing time, reduced stresses (e.g., magnetostriction), and optimized performance of the finished amorphous metal magnetic component. It is particularly advantageous to eliminate the process steps previously required to form and stack a large number of individual stamped laminations. Conventional dies are relatively expensive to manufacture and have a limited useful life when stamping amorphous metal. In addition, the process of the present invention is more flexible in accommodating design changes without the disadvantage of having to amortize the cost of mold manufacture in high volume production. A motor having a large diameter can be easily manufactured with high efficiency using a magnetic material, which does not excessively generate useless waste. These advantages are difficult or impossible to achieve using conventional motors and conventional production techniques associated therewith.

The electrical machine of the invention is particularly advantageous in applications requiring high efficiency, high rotational speed and high power density. The reduced core losses provided by the magnetic component of the present invention improve the efficiency of the motor and provide an improvement in increasing the rotational speed. In addition, the lower core losses compared to components constructed using steels that are conventional in the motor art allow the components and motors of the present invention to be excited at higher frequencies without unacceptable heating due to core losses. The motor can thus be operated at a higher rotational speed. For comparable torque levels, an increase in speed increases the power output proportionally, resulting in a higher power density, i.e. a higher power output to motor weight ratio, as well.

Brief description of the drawings

A more complete understanding of the present invention and further advantages thereof may be acquired by referring to the following detailed description of the invention taken in conjunction with the accompanying drawings, in which like reference numbers indicate like parts throughout the views, and wherein:

figure 1 is a perspective view of a unitary amorphous metal magnetic component for use in an axial flux electric motor;

FIG. 2 is an exploded view depicting a unitary amorphous metal stator and a unitary amorphous metal rotor for incorporation in an induction machine according to the present invention;

FIG. 3 is a schematic perspective view of an axial flux induction electric machine incorporating a unitary amorphous metal stator constructed in accordance with the present invention; and

fig. 4 is a plan view of a permanent magnet rotor for an axial flux permanent magnet dc motor of the present invention.

Detailed description of the preferred embodiments

The present invention provides a method of constructing a unitary amorphous metal magnetic component for use in a high efficiency, axial-flux electric machine. The component may be a rotor or a stator having a generally cylindrical shape and comprising helically wound strips of ferromagnetic amorphous metal. A plurality of teeth project axially from the annular back iron portion. The layers are preferably electrically insulated from each other to reduce eddy current losses. The amorphous metal component of the present invention has significantly lower core losses than similar components of the prior art, thereby improving the efficiency of electric machines employing such new components.

Previous attempts to construct axially spaced machines using amorphous metals have not resulted in a wide range of commercial applications due to geometric limitations and the lack of suitable means to form the required components by conventional stamping, machining and other cutting means.

However, there is still a need for further improvements in motor components with significantly improved ac magnetic performance; the most important property is lower core loss. The desired combination of high magnetic flux density, high permeability and low core loss can be provided by using the magnetic component of the present invention in the construction of an electrical machine.

Referring now in detail to the drawings, there is shown in fig. 1 a unitary amorphous metal magnetic component 21 of the present invention for use in an axial flux electric motor. Component 21 comprises a spirally wound amorphous metal strip or ribbon 34 forming a cylindrical shape having opposed annular faces 22 and 24 and cylindrical inner and outer surfaces 33 and 27. The cylindrical shape has an inner diameter D and an outer diameter D. The annular faces 22, 24 are separated by a thickness L. A plurality of slots 26 for receiving conductors (not shown) extend from the inner surface 33 to the outer surface 27. Those skilled in the art will recognize that the conductors may take different forms depending on the type of electric machine in which the stator is used. The conductor may be a stent or similar element that acts as a collapsible secondary coil. Alternatively, the conductor may comprise an electrical winding arranged to be energised by the flow of current supplied thereto. Each groove 26 has a width W measured at the outer surface 27 and a depth T measured from the annulus 22. Slots 26 are formed by cutting a wound cylinder of amorphous metal to form a plurality of teeth 34 extending axially from a generally annular back iron portion 35. The component may employ any number of slots that meet the mechanical and operational requirements of the motor. The monolithic part 21 is impregnated with epoxy resin in order to make it sufficiently structurally and mechanically integral for the assembly and operation of the motor to which it is coupled.

Figure 2 shows a stator assembly 20 comprising a first core 21 similar to that shown in figure 1 and conductive windings 28 surrounding teeth 34 in an arrangement known to those skilled in the art of electric motors. Fig. 2 also shows a rotor 40 comprising a similar second core 41 having two opposite annular faces 42 and 44. The annulus 42 has a plurality of radial slots 46 for receiving conductors therein. As can be seen in fig. 2, the conductors for the rotor 40 in the illustrated embodiment take the form of brackets 48. The support acts as a shortenable secondary coil that can generate a magnetic field induced by the magnetic field in the winding 28. The two magnetic fields act in opposition to produce a force that rotates the rotor 40. Although the bracket 48 is shown in the form of a one-piece casting, the bracket may be formed from a plurality of stacked stampings. In addition, although not shown, a wound rotor employing windings, slip rings, and resistors that shorten the windings may be utilized in place of the brackets 48. The core for the stator 20 and rotor 40 may be formed in a similar manner from helically wound strips of amorphous metal material as described in connection with fig. 1. The windings 28 are energized by a motor drive circuit (not shown) of conventional design to provide a source of electrical current that generates magnetic flux to operate a motor constructed in accordance with the rotor and stator of the present invention.

Fig. 3 shows an exemplary axial flux induction electric machine 10 of the present invention constructed using a unitary amorphous metal stator assembly 20 fixedly attached to a frame 30 and a disc-shaped permanent magnet rotor 40 mounted on a shaft 29, wherein the shaft 29 is rotatably mounted in bearings 32 journalled within the frame 30. The rotor 40 and the stator 20 are mounted on the frame 30 such that an air gap 31 is formed therebetween. The rotor and stator are preferably identical in size, having substantially equal inner and outer diameters.

Fig. 4 shows a disc-shaped annular permanent magnet rotor assembly 60 for use in the brushless axial flux dc motor of the present invention in conjunction with the unitary stator core 21 shown in fig. 1. The rotor 60 includes six circumferentially disposed magnetic segments 62. The segments are permanently magnetized in alternating directions to provide poles of opposite polarity. The segments are labeled N and S to indicate the respective magnetic north and south poles present on the surface of each segment 62. Each magnetic segment 62 may comprise a permanent magnet (e.g., ferrite or rare earth magnet) adhesively secured to an annular backing plate 64. In the illustrated embodiment, the surface of the support plate 64 is provided with a recess 66 defined by a wall 68 for receiving the segment 62. The segments 62 may be pre-magnetized prior to assembly of the rotor 60, but are preferably magnetized post-assembly using techniques known in the magnetic arts. The magnetization pattern provides magnetic flux directed generally perpendicular to the surface of the rotor assembly, wherein the magnetic flux is alternately directed into and out of the surface plane of alternating segments. The annular inner surface 72 of the rotor assembly 60 defines the central aperture 70 therein. Shaft 29 passes through bore 70 and is attached to rotor assembly 40 using known means including, but not limited to, interference fit, welding, brazing, soldering, gluing, threaded engagement, riveting, pinning, etc. Alternatively, the bearing plate 64 may be a solid structure without a central bore, in which case one end of the shaft 29 may be directly connected to the plate 64 by known means, or to a flange structure (not shown) associated with the plate.

Advantages realized in the construction of an axial flux motor in accordance with the present invention, as a result of the incorporation of one or more unitary amorphous metal components, include simplified manufacturing, reduced manufacturing time, reduced stresses (i.e., magnetostriction), reduced core loss, and optimized performance of the finished motor during construction of the amorphous metal components.

Those skilled in the art will recognize that the term "electric motor" as used herein generally refers to a variety of rotating electrical machines that also include generators and regenerative motors that may be selectively operated as generators. The amorphous metal component described above may be used to construct any of these devices. The components used herein are suitable for constructing motors of a wide variety of types, sizes and power ratings, including micro-motors for microelectronics and actuators, up to integer horsepower motors for traction and large industrial applications. The component is suitable for use in different types of axial flux motors, including, inter alia, brushless and brushed types of dc motors, switched reluctance motors, other synchronous motors, and induction motors. One skilled in the art will also appreciate that an axial flux motor may include one or more rotors and one or more stators. Thus, the terms "rotor" and "stator" as used herein in relation to an electrical machine include a plurality of rotors and stators, ranging in number from one to three or more. For example, one form of brushless, permanent magnet dc motor of the present invention comprises a disc-shaped rotor and two generally mirror-image stators, one stator being coaxially disposed on each of the opposite flat sides of the rotor. Brushless permanent magnet dc motors may also be provided having two rotors, each rotor having two substantially mirror image stators, one stator being provided on each side of each rotor, and the rotors and stators being coaxial with one another.

Conventional design considerations generally dictate that radial flux machines must be made relatively long in order to provide high shaft torque and high output power. Typically, a wide range of power rated motor designs are based on selecting from a small number of standard laminations, and the nameplate rating can be adjusted by varying the overall stack length. By limiting the number of such structures, the cost of manufacturing different die sets can be reduced, and the standard diameter can be selected to reduce the amount of inevitable scrap. In contrast, the axial-flux electric machine of the present invention can achieve high torque and high power through a shorter shaft length and a larger diameter. The power rating can be easily adjusted by changing the diameter of the motor. Furthermore, the axially spaced configuration is highly advantageous for many applications where a longer axial length for mounting the motor is not available despite the greater lateral spacing. Such requirements are commonly found in automotive applications, including traction motors for electric or hybrid vehicles, and direct-drive starter-alternator systems mounted near the flywheel of the vehicle's internal combustion engine. Such a system also utilizes a high pole count design, which can be achieved with the low loss amorphous metal components and electric machines presented herein. Those skilled in the art will recognize other applications in which the flat, compact geometry of the motor of the present invention is advantageous.

The three-dimensional magnetic component 21 or 41 configured as described above has a low core loss. When excited to a peak induction level B at an excitation frequency "f_max"or" may have an iron loss less than "L" at room temperature, where L is represented by the formula L0.0074 f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4Core loss, excitation frequency and peak induction levels are given in watts/kilogram, hertz and tesla, respectively. In another embodiment, the magnetic component may have (i) an amorphous metal material core loss equal to or less than about 1 watt/kg when operated at a frequency of about 60 hertz and a flux density of about 1.4 tesla (T); (ii) an amorphous metal material having a core loss of about 12 watts per kilogram or less when operated at a frequency of about 1000 hertz and a flux density of about 1.0T; or (iii) an amorphous metal material having a core loss of equal to or less than about 70 watts per kilogram when operated at a frequency of about 20000 hertz and a flux density of about 0.30T. The reduced core loss of the component advantageously increases the efficiency of an electrical device incorporating the component.

The lower core loss values make the monolithic magnetic component particularly useful in applications where the component is subjected to high frequency magnetic excitation, such as excitation occurring at a frequency of at least about 100 hertz. The inherent high core loss of conventional steels at high frequencies makes them unsuitable for use in devices requiring high frequency excitation. These core loss performance values apply to the various embodiments of the component regardless of the particular geometry of the bulk amorphous metal component.

For example, any synchronous motor operates at a rotational speed proportional to the ratio of the excitation frequency to the number of poles in the motor. By using the above-described amorphous metal components rather than conventional steel components, such motors can be designed with a much higher number of poles. However, the motor can still operate at the same speed, since the required increase in excitation frequency does not result in excessive core loss. This flexibility is particularly desirable in variable speed applications. In many cases, the ability to operate over a wide speed range will allow the designer to eliminate the gear set or transmission system required by conventional motors. Eliminating these parts from the mechanical system improves efficiency and reliability. These characteristics are particularly useful when the motor of the present invention is used, for example, in vehicle traction applications.

In addition, the low core loss of the disclosed component allows it to be excited at higher frequencies than prior art motor components constructed of electrical and motor steels. Such energization of the prior art components will likely generate sufficient heat to raise the temperature of the motor to a level that would damage the wire insulation and other materials commonly used in motor construction. Thus, motors constructed using the components of the present invention can operate at higher rotational speeds, thus delivering higher mechanical power and providing higher power density for a given level of torque.

The unitary amorphous metal magnetic component of the present invention may be fabricated using a variety of ferromagnetic amorphous metal alloys commonly known as strip, bar or ribbon shapes. Generally, the amorphous metal suitable for use in the component consists essentially of a metal having the formula M_70-85Y_5-20Z_0-20Wherein "M" is at least one of iron, nickel, and cobalt, "Y" is at least one of boron, carbon, and phosphorus, "Z" is at least one of silicon, aluminum, and germanium; with the proviso that (i) up to ten percent (10%) atomic percent of component "M" may be replaced by at least one of the metallic species titanium, vanadium, chromium, manganese, copper, zirconium, niobium, molybdenum, tantalum, hafnium, silver, gold, palladium, platinum and tungsten, (ii) up to ten percent (10%) atomic percent of component (Y + Z) may be replaced by at least one of the non-metallic species indium, tin, antimony and lead; (iii) up to about one percent (1%) atomic percent of component (M + Y + Z) may be incidental impurities. As used herein, the term "amorphous metal alloy" refers to a metal alloy that is substantially devoid of any long-range order and can be characterized by an X-ray maximum diffraction intensity that is qualitatively similar to that observed in liquid or inorganic oxide glasses.

Alloys suitable for use in making the component are ferromagnetic at the temperature at which the component is used. Ferromagnetic materials can exhibit spatial alignment of the magnetic moments of their constituent atoms and strong long-range coupling when exposed to temperatures below the material's characteristic temperature (commonly referred to as the curie temperature). The Curie temperature of the material used in the apparatus operating at room temperature is preferably at least about 200 deg.C, and most preferably at least about 375 deg.C. If the material to be included has an appropriate Curie temperature, the device may operate at other temperatures, including as low as cryogenic temperatures or high temperatures.

As is known, a ferromagnetic material can also be characterized by its saturation induction or, equivalently, by its saturation flux density or magnetization. One suitable alloy has a saturation induction of at least about 1.2 tesla (T), and more preferably at least about 1.5T. The alloy also has a high electrical resistivity of at least about 100 μ Ω -cm, preferably at least about 130 μ Ω -cm.

Amorphous metal alloys suitable for use as feedstock are commercially available, typically in widths of 20 cm or moreAnd in the form of a continuous thin ribbon or strip having a thickness of about 20-25 microns. These alloys form a substantially fully glassy microstructure (e.g., at least about 80% by volume of material having an amorphous structure). The alloy may suitably be formed of a material having almost 100% amorphous structure. The volume fraction of the amorphous structure can be determined by methods known in the art, such as X-ray, neutron or electron diffraction, transmission electron microscopy, or differential scanning calorimetry. For alloys in which "M", "Y" and "Z" are predominantly iron, boron and silicon, respectively, the highest induction values can be achieved at low cost. More specifically, one suitable alloy comprises at least 70 atomic percent iron, at least 5 atomic percent boron, and at least 5 atomic percent silicon, with the proviso that the total content of boron and silicon is at least 15 atomic percent. Also for this reason, amorphous metal strip composed of an iron-boron-silicon alloy is preferred. One suitable amorphous metal strip has a composition comprising about 11 atomic percent boron and about 9 atomic percent silicon, with the balance being iron and incidental impurities. Such a strip has a saturation induction of about 1.56T and a resistivity of about 137 μ Ω -cm, and is manufactured by Honeywell International IncSold under the trade name alloy 2605 SA-1. Another suitable amorphous metal strip has a composition consisting essentially of about 13.5 atomic percent boron, about 4.5 atomic percent silicon, and about 2 atomic percent carbon, with the balance being iron and incidental impurities. Such a strip has a saturation induction of about 1.59T and a resistivity of about 137 μ Ω -cm, and is manufactured by Honeywell International IncSold under the trade name alloy 2605 SC. For applications requiring higher saturation induction, the composition of a suitable strip consists essentially of iron, with about 18 atomic percent cobalt, about 16 atomic percent boron, about 1 atomic percent silicon, and the balance iron and incidental impurities. Such tapes are produced by Honeywell InternaNational Inc. toSold under the trade name alloy 2605 CO. However, the loss of a component constructed from this material is slightly higher than the loss of a component constructed using METGLAS 2605 SA-1.

The mechanical and magnetic properties of the amorphous metal strip used in the component are typically enhanced by heat treatment at a temperature and for a time sufficient to provide the desired enhancement without altering the substantially fully glassy microstructure of the strip. The heat treatment includes a heating section, an optional holding section, and a cooling section. Alternatively, a magnetic field may be applied to the strip during at least a portion of the heat treatment, such as at least during the cooling portion. The magnetic field is preferably applied substantially along the direction in which the magnetic flux is located during operation of the stator, and in some cases may also improve the magnetic properties of the component and reduce its core loss. Alternatively, the heat treatment may comprise more than one such thermal cycle.

The magnetic properties of certain amorphous alloys suitable for use in a unitary amorphous metal component may be significantly enhanced by heat treating the alloy to form a nanocrystalline microstructure therein. The microstructure can be characterized by the presence of a high density of grains having an average grain size of about 100 nanometers or less, preferably 50 nanometers or less, and more preferably 10 to 20 nanometers. The grains preferably constitute at least 50% by volume of the iron-based alloy. These materials have low core loss and low magnetostriction. The low magnetostriction properties also make the material less susceptible to degradation of magnetic properties due to stresses formed during manufacture and/or operation of the component. The heat treatment required to form the nanocrystalline structure in a given alloy must be performed at a higher temperature or for a longer time than that required for a heat treatment designed to maintain a substantially fully glassy microstructure therein. The terms "amorphous metal" and "amorphous alloy" as used herein also include materials that initially form a substantially fully glassy microstructure that is subsequently converted to a material having a nanocrystalline microstructure by heat treatment or other processing. Amorphous alloys that can be heat treated to form a nanocrystalline microstructure are also referred to simply as nanocrystalline alloys. The method of the present invention allows the nanocrystalline alloy to be formed into a finished stator of a desired geometry. Such shaping may be advantageously achieved while the alloy is still in its as-cast, ductile, substantially amorphous form, and before it is heat treated to form a nanocrystalline structure that may make it more brittle and more difficult to handle.

Two classes of alloys having significantly improved magnetic properties by forming nanocrystalline microstructures therein are given by the following formula where the subscripts are atomic percent.

The first type of nanocrystalline material consists essentially of Fe having the formula_{100-u-x-y-z-w}R_uT_xQ_yB_zSi_wWherein R is at least one of nickel and cobalt, T is at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten, Q is at least one of copper, silver, gold, palladium, and platinum, u ranges from 0 to about 10, x ranges from about 3 to 12, y ranges from 0 to about 4, z ranges from about 5 to 12, and w ranges from 0 to less than about 8. The alloy is then heat treated to form therein a nanocrystalline microstructure having a relatively high saturation induction (e.g., at least about 1.5T), relatively low core loss, and relatively low saturation magnetostriction (e.g., less than 4X 10 absolute values)^-6Magnetostriction of (1). Such alloys may be used in applications where a minimum sized motor is required for the required power and torque.

The second type of nanocrystalline material consists essentially of a material having the formula Fe_{100-u-x-y-z-wRu}T_xQ_yB_zSi_wWherein R is at least one of nickel and cobalt, T is at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten, Q is at least one of copper, silver, gold, palladium, and platinum, u ranges from 0 to about 10, x ranges from about 1 to 5, y ranges from 0 to about 3, z ranges from about 5 to 12, and w ranges from about 8 to 18. The alloy is then heat treated toIn which a nanocrystalline microstructure is formed having a saturation induction of at least about 1.0T, particularly low core loss, and low saturation magnetostriction (e.g., less than 4 x 10 absolute)^-6Magnetostriction of (1). Such alloys may be used in motors that are required to operate at very high speeds (e.g., requiring excitation frequencies of 1000 hz or higher).

A method for constructing a unitary amorphous metal component is also provided. In general, the method comprises the steps of: (i) helically winding a ferromagnetic amorphous metal strip material to form a wound cylinder of annular cross-section having a cylindrical inner surface, a cylindrical outer surface and two opposed annular faces separated by an axial thickness; (ii) carrying out heat treatment on the cylinder; (iii) bonding each layer of the wound cylinder to the layer adjacent thereto with an adhesive; and (iv) forming the component by cutting a plurality of grooves into at least one of the annular faces, the grooves extending generally radially between the inner and outer surfaces and having a depth less than the axial thickness. The adhesive bonding is preferably carried out by impregnation. Alternatively, a finishing step (v) may be performed, including coating the component to obtain a suitable surface finish. The heat treatment step includes one or more heat treatments to alter the mechanical or magnetic properties of the amorphous metal feedstock. This optional heat treatment facilitates the machining operation and improves the magnetic properties of the part. Steps (i) to (v) may be performed in a variety of orders and using a variety of techniques including those described below. For example, the heat treatment step (ii) may optionally be carried out after the bonding step (iii) or after the forming step (iv).

The heat treatment of the amorphous metal may be performed using any heating means that can subject the metal to the desired thermal profile. Suitable heating means include infrared heat sources, furnaces, fluidized beds, thermal contact with a heat sink maintained at an elevated temperature, resistive heating by passing an electric current through the strip, and inductive (radio frequency) heating. The heating means may be selected according to the order of the desired processing steps listed above. A magnetic field may be selectively applied to the amorphous metal during at least a portion of the heat treatment, such as the cooling portion.

Heat treatment of amorphous metal materials can alter their mechanical properties. Specifically, heat treatment generally reduces the ductility of the amorphous metal, thereby limiting the amount of mechanical deformation of the amorphous metal prior to fracture, which in some cases facilitates the cutting of the hard amorphous metal to form the teeth of the inventive component.

Bonding means are used to bond the layers of amorphous metal material to each other to provide a monolithic three dimensional object with sufficient structural integrity to allow the grooves required for the component of the invention to be cut or machined. Integrity also facilitates handling and use of the component and incorporation into larger structures. A variety of adhesives are suitable. The adhesive preferably has low viscosity, low shrinkage, low elastic modulus, high peel strength, and high dielectric strength. The adhesive preferably has a viscosity of less than 1000cps and a coefficient of thermal expansion approximately equal to that of the metal, i.e., about ten parts per million. Preferred adhesives include at least one selected from the group consisting of varnishes, anaerobic adhesives, and Room Temperature Vulcanizing (RTV) silicone materials. A more preferred adhesive is a cyanoacrylate, such as methyl cyanoacrylate sold under the trade name Permabond 910FS by National Starch and Chemical Company. The device of the invention is preferably bonded by applying such an adhesive such that it penetrates between the layers of the tape by capillary action. Permabond 910FS is a one-part, low viscosity liquid that cures in about 5 seconds at room temperature. Another more preferred adhesive is an epoxy resin, which may be in the form of multiple components whose curing is effected by chemical activation, or in the form of a single component whose curing is activated by thermal activation or by exposure to ultraviolet radiation. The most preferred adhesive is a low viscosity heat activated epoxy such as that sold under the trade name Epoxylite 8899 by the company p.d. george co. The device of the invention is preferably bonded by impregnation with such an epoxy resin diluted with acetone in a 1: 5 volume ratio in order to reduce its adhesion and improve its penetration between the layers of the tape.

The adhesive may be applied to the tape before the tape is wound to form the cylinder used to make the component of the invention. Suitable methods of applying the adhesive include dipping, spraying, brushing, and electrostatic deposition. Amorphous metal strip may also be coated by passing it over rods or rollers that transfer adhesive to the amorphous metal. A rod or roll with a textured finish, such as a gravure roll or a wire-wound roll, is particularly effective for transferring a uniform coating of adhesive onto amorphous metal. Alternatively and more preferably, the adhesive may be collectively applied thereto after all the layers of the metal are laminated. Preferably, the wound cylinder is impregnated by capillary flow of the adhesive between the layers. The cylinder may be placed under vacuum or hydrostatic pressure for more complete filling. This process results in a reduction in the total volume of adhesive added, thereby ensuring a higher lamination factor. Activation or curing of the adhesive may also be used to affect magnetic properties as described above if performed at a temperature of at least 175 ℃.

Grooves may be formed in the magnetic component of the present invention using any known technique including, but not limited to, mechanical grinding, diamond wire cutting, high speed milling in a horizontal or vertical orientation, abrasive water jet milling, electrical discharge machining by wire or punch-through, electrochemical grinding, electrochemical machining, and laser cutting. Preferably, the cutting process does not produce any significant damage at or near the cutting face. Such damage comes, for example, from excessive cutting speeds, which locally heat the amorphous metal above its crystallization temperature, or even melt the material at or near the edge. Adverse consequences may include increased stress and core loss near the edges, layer-to-layer shorting, or degradation of mechanical properties.

A preferred method for cutting grooves into the components of the present invention includes electrochemical grinding. This technique removes material from the component by a combination of electrochemical and mechanical action. The current passes from the electrically conductive rotating cutting wheel through the electrolyte and into the likewise electrically conductive component. When current flows between the cutting wheel and the component, the electrolyte dissolves the component and forms a soft metal oxide. The cutting wheel removes oxide with a small amount of heating and deformation of the part, thereby providing efficient, rapid and accurate manufacture of the parts of the invention.

As described above, the magnetic component of the present invention has a lower core loss than a similarly sized component made of conventional steel. As is known in the art, core loss refers to the dissipation of energy generated within a ferromagnetic material as the magnetization of the ferromagnetic material changes over time. The core loss of a given magnetic component is typically determined by periodically energizing the component. A time-varying magnetic field is applied to the component in order to generate therein a corresponding time-varying magnetic induction or flux density. For the standardization of the measurement, the excitation is generally chosen such that the magnetic induction varies sinusoidally with time at a frequency "f" and has a peak amplitude "B_max". The core loss is then determined by known electrical measurement equipment and techniques. Core loss is typically expressed in watts per unit mass or volume of the excited magnetic material. It is known in the art that the core loss varies with f and B_maxMonotonically increases.

Standard provisions for measuring the core loss of soft magnetic materials are known (e.g., ASTM standards A912-93 and A927 (A927M-94)). They generally require a sample of such a material which is arranged in a rather closed magnetic circuit, i.e. a configuration in which closed magnetic flux lines are completely contained in the sample volume. Such sample forms include tape-wound or punched spiral tubes, individual strips passing through a magnetic yoke, or laminated forms such as an epstein-barr. These forms also have a fairly uniform cross-section from end to end, allowing the test to be performed at a well-defined magnetic flux density. On the other hand, the magnetic material employed in the motor components is arranged in an open-loop magnetic circuit, i.e. a configuration in which the magnetic flux lines have to cross the air gap. Due to fringing field effects and inhomogeneity of the magnetic field, a given material tested in open circuit typically has a higher core loss, i.e. a higher value of watts per unit mass or volume, than in closed circuit measurements. The above-described monolithic magnetic component advantageously exhibits low core loss over a wide range of flux densities and frequencies, even in an open circuit configuration.

Without being bound by any theory, it is believed that the total iron loss of a low-loss bulk amorphous metal component includes contributions from hysteresis losses and eddy current losses. Each of these two effects is the peak magnetic induction B_maxAnd the excitation frequency f. The magnitude of the various effects also depends on extrinsic factors, including the method of construction of the component and the thermo-mechanical experience of the materials used for the component. Prior art analyses of core loss in amorphous metals (see, e.g., g.e.fish, j.appl.phys).573569(1985) and g.e.fish et al, j.appl.phys.645370(1988)) are generally limited to data obtained from material within a closed magnetic circuit. The low hysteresis and eddy current losses in these analyses are due in part to the high resistivity of amorphous metals.

Total iron loss per unit mass L (B) of the monolithic magnetic component of the present invention_maxF) can be roughly determined by the following equation:

L(B_max，f)＝c₁f(B_max)ⁿ+c₂f^q(B_max)^m

wherein the coefficient c₁And c₂And the indices n, m and q must all be determined empirically, there is no known theory to determine their values accurately. Using this formula allows the total core loss of the monolithic magnetic component to be determined at any desired operating induction and excitation frequency. It is generally found that the magnetic field therein is spatially inhomogeneous under the specific geometry of the motor components, such as the rotor or the stator. Techniques such as finite element modeling are known in the art that can provide an estimate of the spatial and temporal variation of the peak flux density, which is very close to the flux density distribution measured in an actual monolithic magnetic component. By taking as input the appropriate empirical formula that gives the core loss of a given material at a spatially uniform flux density, these techniques are allowed to operate with reasonable accuracyThe corresponding actual core loss of a given component in its operating configuration is predicted.

The actual measurement of the core loss can be performed using conventional methods. The magnetomotive force is applied by passing a current through a first winding that surrounds the magnetic component. The resulting magnetic flux density is measured by faraday's law from the voltage induced in the second winding surrounding the magnetic component to be tested. The applied magnetic field is measured from the magnetomotive force by ampere's law. The core loss is then calculated from the applied magnetic field and the resulting magnetic flux density by conventional means such as an electronic wattmeter.

The following examples are provided to more fully describe the performance of the components described herein. The specific techniques, conditions, materials, proportions and reported data set forth to illustrate the principles and applications of the present invention are exemplary only, and should not be construed as limiting the scope of the invention.

Example 1

Preparation and electromagnetic testing of a unitary amorphous metal motor stator

Spirally wound Fe of about 26.7 mm width and 0.022 mm thickness₈₀B₁₁Si₉A strip of ferromagnetic amorphous metal to form two substantially identical right circular cylindrical components, each component having about 3300 layers, an outer diameter of 422 mm and an inner diameter of 272 mm, as shown in figure 1. The cylindrical assembly was annealed in a nitrogen atmosphere. The annealing comprises the following steps: 1) heating each component to 360 ℃; 2) incubating at a temperature of about 360 ℃ for about 2 hours; and 3) cooling the components to ambient temperature. Each cylinder assembly was placed in a jig and impregnated with an epoxy resin solution and cured at 177 ℃ for about 2.5 hours. The epoxy resin used is Epoxylite^TM8899 diluted with acetone in a volume ratio of 1: 5 in order to obtain a suitable viscosity. When fully cured, each cylinder assembly is removed from the jig. The assembly weight of each formed epoxy bonded amorphous metal cylindrical segment was about 14 kilograms. Then cutting 72 strips equally spaced in one of the annular end faces of each cylindrical assemblySpaced apart slots. Each groove was 19 mm deep and 5.8 mm wide and extended radially from the inner surface to the outer surface of the cylinder. The cutting is performed by an electrochemical grinding process. The surface of each component is finished after cutting to remove excess epoxy on the surface to form two substantially identical stators for the axially spaced motors. The samples were arranged in a coaxial arrangement with their respective teeth forming mating abutments. Appropriate primary and secondary electrical windings are secured to the cylindrical test sample assembly for electrical testing.

The test assembly showed an amorphous metal material having a core loss value of less than 1 watt/kg when operated at a frequency of about 60 hertz and a flux density of about 1.4 tesla (T), less than 12 watts/kg when operated at a frequency of about 1000 hertz and a flux density of about 1.0 tesla, and less than 70 watts/kg when operated at a frequency of about 20000 hertz and a flux density of about 0.30 tesla. The low core loss of the components of the present invention makes them suitable for use in constructing motor stators.

Example 2

High frequency electromagnetic testing of amorphous metal motor stator

Two cylindrical stators including wound amorphous metal layers were prepared as in example 1. The primary and secondary electrical windings are secured to the stator. Electrical tests were performed at 60, 1000, 5000 and 20000 hertz and at different magnetic flux densities. The core loss values are compiled in tables 1, 2, 3 and 4 below. As shown in tables 3 and 4, the iron loss is particularly low at excitation frequencies of 5000 hz or higher. The stator of the invention is therefore particularly suitable for use in motors operating at high excitation frequencies.

TABLE 1

Iron loss @60 Hz (Tile/kilogram)

TABLE 2

Core loss @1000 Hz (Tile/kilogram)

TABLE 3

Iron loss @5000 Hz (Tile/kilogram)

TABLE 4

Iron loss @20000 hertz (tile/kilogram)

Example 3

High frequency characteristics of low loss bulk amorphous metal component

The iron loss data of example 2 above was analyzed using a conventional non-linear regression method. Can be confirmed to be made of Fe₈₀B₁₁Si₉The core loss of a low-loss, unitary amorphous metal component made of amorphous metal strips can be roughly determined by the following equation:

L(B_max，f)＝c₁f(B_max)ⁿ+c₂f^q(B_max)^m

selection coefficient c₁And c₂And appropriate values for the indices n, m and q to determine an upper limit for the magnetic loss of the bulk amorphous metal component. Table 5 lists the losses of the components in example 2 and the losses predicted by the above formula, both measured in watts per kilogram. Predicted as f (Hertz) and B_maxLoss of function of (Tesla) is taken as c₁0.0074 and c₂0.000282 and n 1.3, m 2.4 and q 1.5. The loss of the bulk amorphous metal component of example 2 was lower than the corresponding loss predicted by the formula.

TABLE 5

Dot	B(Tesla)	Frequency (Hertz)	Core loss of example 1 (Tile/kilogram)	Predicted core loss (Watts/kilogram)
					1	0.3	60	0.1	0.10
2	0.7	60	0.33	0.33
					3	1.1	60	0.59	0.67
4	1.3	60	0.75	0.87
					5	1.4	60	0.85	0.98
6	0.3	1000	1.92	2.04
					7	0.5	1000	4.27	4.69
8	0.7	1000	6.94	8.44
					9	0.9	1000	9.92	13.38
10	1	1000	11.51	16.32
					11	1.1	1000	13.46	19.59
12	1.2	1000	15.77	23.19
					13	1.3	1000	17.53	27.15
14	1.4	1000	19.67	31.46
					15	0.04	5000	0.25	0.61
16	0.06	5000	0.52	1.07
					17	0.08	5000	0.88	1.62
18	0.1	5000	1.35	2.25
					19	0.2	5000	5	6.66
20	0.3	5000	10	13.28
					21	0.04	20000	1.8	2.61
22	0.06	20000	3.7	4.75
					23	0.08	20000	6.1	7.41
24	0.1	20000	9.2	10.59

25	0.2	20000	35	35.02
					26	0.3	20000	70	75.29

Having described the invention in rather full detail, it is to be understood that such detail need not be strictly adhered to but that various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the subjoined claims.

Claims (22)

1. A method of constructing a low core loss, unitary amorphous metal magnetic component for an electric machine comprising the steps of:

spirally winding a ferromagnetic amorphous metal strip material to form a wound cylinder of annular cross-section having cylindrical inner and outer surfaces and two annular faces separated by an axial thickness;

step two, carrying out heat treatment on the cylinder;

bonding each layer of the winding cylinder to the layer adjacent to the winding cylinder by using an adhesive; and

forming the component by cutting a plurality of grooves into at least one of the annular faces, the grooves extending between the inner and outer surfaces and having a depth less than the axial thickness.

2. The method of claim 1, wherein the adhesive comprises at least one selected from the group consisting of a varnish, an anaerobic adhesive, and a Room Temperature Vulcanizing (RTV) silicone material.

3. The method of claim 1, wherein the bonding is achieved by impregnating the cylinder with the adhesive and activating the adhesive.

4. The method of claim 1, wherein the adhesive comprises a cyanoacrylate.

5. The method of claim 1, wherein the adhesive comprises an epoxy.

6. The method of claim 5, wherein the epoxy resin is a low viscosity, heat activated epoxy resin.

7. The method according to claim 1, characterized in that the method further comprises the step of:

and step five, finishing the part by coating to enable the part to have proper surface finish.

8. A method of constructing a low core loss, unitary amorphous metal magnetic component for an electric machine comprising the steps of:

spirally winding a ferromagnetic amorphous metal strip material to form a wound cylinder of annular cross-section having cylindrical inner and outer surfaces and two annular faces separated by an axial thickness;

bonding each layer of the winding cylinder to the layer adjacent to the winding cylinder by using an adhesive;

step three, carrying out heat treatment on the cylinder; and

forming the component by cutting a plurality of grooves into at least one of the annular faces, the grooves extending between the inner and outer surfaces and having a depth less than the axial thickness.

9. A method of constructing a low core loss, unitary amorphous metal magnetic component for an electric machine comprising the steps of:

spirally winding a ferromagnetic amorphous metal strip material to form a wound cylinder of annular cross-section having cylindrical inner and outer surfaces and two annular faces separated by an axial thickness;

bonding each layer of the winding cylinder to the layer adjacent to the winding cylinder by using an adhesive;

shaping the component by cutting a plurality of grooves into at least one of the annular faces, the grooves extending between the inner and outer surfaces and having a depth less than the axial thickness; and

and step four, carrying out heat treatment on the cylinder.

10. The method of claim 1, wherein the heat treatment comprises heating, holding, and cooling, and wherein a magnetic field is applied to the component during at least the cooling.

11. The method of claim 1, wherein the cutting is performed by a process comprising electrochemical grinding.

12. The method of claim 1Characterized in that said ferromagnetic amorphous metal strip material has a structure substantially represented by formula M_70-85Y_5-20Z_0-20A defined composition, subscripts being atomic percentages, wherein "M" is at least one of iron, nickel, and cobalt, "Y" is at least one of boron, carbon, and phosphorus, "Z" is at least one of silicon, aluminum, and germanium; with the proviso that i: up to ten percent (10%) atomic percent of component "M" may be replaced by at least one of the metal species titanium, vanadium, chromium, manganese, copper, zirconium, niobium, molybdenum, tantalum, hafnium, silver, gold, palladium, platinum, and tungsten, ii: up to ten percent (10%) atomic percent of the component Y + Z may be replaced by at least one of the non-metallic substances indium, tin, antimony, and lead; iii: up to about one percent (1%) by atomic percentage of the components M + Y + Z are incidental impurities.

13. A method according to claim 1 wherein said ferromagnetic amorphous metal strip material has a composition comprising at least 70 atomic percent iron, at least 5 atomic percent boron, and at least 5 atomic percent silicon, with the proviso that the total content of boron and silicon is at least 15 atomic percent.

14. The method of claim 13, wherein the M component is iron, the Y component is boron, and the Z component is silicon.

15. The method as claimed in claim 13, wherein said ferromagnetic amorphous metal strip material has a chemical formula of Fe₈₀B₁₁Si₉To determine the composition.

16. The method of claim 1 wherein said heat treating step forms a nanocrystalline microstructure in said amorphous metal strip.

17. The method of claim 16Method, characterized in that said ferromagnetic amorphous metal strip material has a structure substantially represented by the formula Fe_{100-u-x-y-z-w}R_uT_xQ_yB_zSi_wA defined composition, wherein R is at least one of nickel and cobalt, T is at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten, Q is at least one of copper, silver, gold, palladium, and platinum, u ranges from 0 to 10, x ranges from 3 to 12, y ranges from 0 to 4, z ranges from 5 to 12, and w ranges from 0 to less than 8.

18. The method as recited in claim 16 wherein said ferromagnetic amorphous metal strip material has a composition generally represented by the formula Fe_{100-u-x-y-z-w}R_uT_xQ_yB_zSi_wA defined composition, wherein R is at least one of nickel and cobalt, T is at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten, Q is at least one of copper, silver, gold, palladium, and platinum, u ranges from 0 to about 10, x ranges from about 1 to 5, y ranges from 0 to about 3, z ranges from about 5 to 12, and w ranges from about 8 to 18.

19. A low core loss, unitary amorphous metal component constructed according to the method of claim 1.

20. A low core loss, unitary amorphous metal component according to claim 19, when operated at an excitation frequency "f" to a peak induction level "B_max"wherein L is represented by the formula L ═ 0.0074f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4The core loss, the excitation frequency and the peak induction level are given as measured in watts/kilogram, hertz and tesla, respectively.

21. An axial flux electric motor comprising at least one low core loss, unitary amorphous metal component constructed according to the method of claim 1.

22. The axial flux electric motor of claim 21, when operated to peak induction level "B" at excitation frequency "f_max"wherein L is represented by the formula L ═ 0.0074f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4The core loss, the excitation frequency and the peak induction level are given as measured in watts/kilogram, hertz and tesla, respectively.