JP2019116971A - Wave gear device, circular spline and method - Google Patents

Abstract

To provide a flexible spline as a component of a wave gear device having a sufficient flexibility durable against high frequency cycle deformation and simultaneously having a sufficient strength adapted for a load to which the wave gear device is exposed.SOLUTION: A bulk metallic glass system wave gear device and a wave gear device component are realized by a system and a method of the preferred embodiment of this invention. In one preferred embodiment, the wave gear device comprises a wave generator, a flexible spline having a first gear set as it is and a circular spline having a second gear set as it is. At least one of the wave generator, the flexible spline and the circular spline includes a bulk metal glass system material.SELECTED DRAWING: Figure 1

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT The invention disclosed herein is made in the context of contracted work with NASA, and also requires that the Contractor maintain the title. )
Under the control of

The present invention relates generally to bulk metal glass based strain wave gears and wave gear set components.

Wave gearing, also known as Harmonic Drive®, is a unique gearing system, with high reduction ratio, high torque-weight ratio and torque-volume ratio, nearly zero backlash (potential of components Wear can be reduced), and many other benefits can be provided. Usually, the wave gear device is a flexspline
With an elliptical wave generator mounted in it, the flexspline being matched to the elliptical waveform by the wave generator (wave generator), this configuration more generally comprising a set of ball bearings The splines rotate about the elliptical central axis with respect to the wave generator. The flexspline is usually arranged in a ring-shaped circular spline and the flexspline has at its outer side an elliptical set of gear tooth sets arranged along the outer periphery, which gear tooth sets are: Engages with gear teeth arranged along the inner circumference of a rim-like circular spline (circular spline). Usually, a flexspline has fewer teeth than a circular spline. In particular, the flexspline is formed from a flexible material, and when the gear teeth of the flexspline and the circular spline mesh, the wave generating device can rotate in a first direction with respect to the circular spline, whereby in the opposite second direction Produce flexspline deformation and associated rotation. Normally, the input torque is supplied to the wave generator and the flexspline results in an output torque. In general, the rotational speed of the wave generator is substantially faster than that of the flexspline. Thus, wave gear arrangements can achieve high reduction ratios for gear systems and can be realized with smaller form factors.

It is also noted that in some alternative configurations, the flexspline can be held stationary and circular splines can be used to generate the output torque.

As can be inferred, the operation of the wave gearing has a particular significance and relies on a very accurately designed gear system. For example, the geometry (geometrical surface shape) of components in wave gear arrangements must be made with extreme precision in order to produce the desired motion. Furthermore, the components of the wave gear device have to be made of materials from which the desired function can be obtained. In particular, the flexspline must have sufficient flexibility to withstand high frequency cyclic deformation, while at the same time sufficient to accommodate the load to which the wave gearing is expected to be exposed. It must have sufficient strength.

Because of these limitations, conventional wave gearing devices have been fabricated from steel in large sizes, as it has been demonstrated that steel has the necessary material properties, and steel is machined to the desired geometry. Because you can do it. However, machining steel as a component can be quite expensive. For example, in many cases, steel-based wave gear devices can cost up to 1000 for expensive manufacturing processes.
The cost may be in the order of dollars to $ 2000.

In some cases, the harmonic drive is made of a thermoplastic material. Thermoplastic materials (e.g. polymers) can be cast (e.g., by an injection molding process) into the shape of the constituent components, whereby expensive, commonly practiced in the manufacture of steel based wave gear devices Machining process can be avoided. However, wave gear devices made of thermoplastic materials do not have the same strength as wave gear devices made of steel.

Systems and methods according to embodiments of the present invention embody wave gearing and wave gearing components based on bulk metal glass. In one embodiment, the wave gearing comprises a wave generator, a flexspline with its own first gear set, and a circular spline with its own second gear set. And at least one of the wave generating device, the flexspline, and the circular spline includes a bulk metallic glass based material.

  In another embodiment, the wave generator comprises a wave generator plug and a bearing.

  In yet another embodiment, the bearing is a ball bearing.

In another embodiment, each of the wave generating device, the flexspline, and the circular spline comprises a bulk metallic glass based material.

In yet another embodiment, at least one of the first set of gear teeth and the second set gear teeth comprises a bulk metallic glass based material.

In yet another embodiment, each of the first set of gear teeth and the second set of gear teeth comprises a bulk metallic glass based material.

In yet another embodiment, the wave generating device comprises a ball bearing comprising a bulk metallic glass based material.

In yet another embodiment, the element of the bulk metallic glass-based material present in the largest amount is F
It is one of e, Zr, Ti, Ni, Hf and Cu.

In yet another embodiment, the element of the bulk metallic glass-based material is Ni ₄₀ Zr _28.
5 Ti _16.5 Al ₁₀ Cu ₅ In yet another embodiment, the wave generating device comprises a wave generating device plug having an oval cross-sectional view, and a bearing having an inner race, an outer race, and a plurality of rolling members, the wave generating device plug being a bearing Located within, so that the bearing can conform to the elliptical shape of the wave generator plug, at least one of the wave generating plug and the bearing comprises a bulk metallic glass based material.

  In another embodiment, the bearing is a ball bearing.

In yet another embodiment, the flexspline comprises a flexible body defining a circular shape, the perimeter of the circular shape defining a set of gear teeth, and the flexible body comprising a bulk metallic glass based material .

  In yet another embodiment, the set of gear teeth comprises a bulk metallic glass based material.

In yet another embodiment, the circular spline comprises a ring shaped body, the inner circumference of the ring shaped body defines a set of gear teeth, and the ring shaped body comprises a bulk metallic glass based material.

  In a further embodiment, the set of gear teeth comprises a bulk metallic glass based material.

In yet another embodiment, a method of making a wave gear assembly component comprises forming a BMG-based material using a mold associated with one of thermoplastic forming and casting techniques, wherein the BMG-based material Wave generator plug, inner race, outer race, rolling elements, flexspline, flexspline without a set of gear teeth, circular spline, circular spline without a set of gear teeth, inside flexspline Forming as one of a set of gear teeth to be incorporated into and a set of gear teeth to be incorporated into a circular spline.

In yet another embodiment, the method of making the wave gear assembly component further comprises the step of machining the BMG-based material after forming by either thermoplastic forming or casting techniques.

In another embodiment, the BMG-based material is formed as one of a flexspline without a set of gear teeth set and a circular spline without a set of gear teeth set, and the gear teeth to the BMG-based material Machined.

In yet another embodiment, the BMG-based material is formed as one of a flexspline without a set of gear teeth and a circular spline without a set of gear teeth, and the gear teeth are twin roll formed Implement for BMG-based materials using technology.

In still other embodiments, the BMG-based material is molded using one of direct casting technology, blow molding technology, and centrifugal casting technology.

Fig. 6 shows a wave gear device that can be made from BMG-based materials according to embodiments of the present invention. FIG. 2A illustrates the operation of a wave gear device according to an embodiment of the present invention. FIG. 2B illustrates the operation of a wave gear device according to an embodiment of the present invention. FIG. 2C shows the operation of a wave gear device according to an embodiment of the present invention. FIG. 2D shows the operation of a wave gear device according to an embodiment of the present invention. The normal average life of the wave gear device is shown. 5 illustrates the fatigue properties of a BMG-based material that can be embodied within a wave gear drive component according to an embodiment of the present invention. 5 illustrates the fatigue properties of a BMG-based material that can be embodied within a wave gear drive component according to an embodiment of the present invention. Fig. 6 shows the wear resistance properties of titanium-nium BMG-based materials that can be embodied within a wave gear drive component according to an embodiment of the present invention. Fig. 6 illustrates a method of forming a BMG-based wave gearing component according to an embodiment of the present invention. FIG. 7A illustrates the formation of a gear using casting techniques according to an embodiment of the present invention. FIG. 7B illustrates the formation of a gear using casting techniques according to an embodiment of the present invention. FIG. 7C shows the formation of a gear using a casting technique according to an embodiment of the present invention. FIG. 7D shows the formation of a gear using casting techniques according to an embodiment of the present invention. FIG. 8A illustrates the fabrication of wave gear drive components using casting techniques according to an embodiment of the present invention. FIG. 8B illustrates the fabrication of wave gear drive components using casting techniques in accordance with an embodiment of the present invention. FIG. 8C illustrates the fabrication of wave gear drive components using casting techniques in accordance with an embodiment of the present invention. FIG. 8D illustrates the fabrication of wave gear drive components using casting techniques according to an embodiment of the present invention. FIG. 9A illustrates the fabrication of a wave gear device component using BMG-based material in sheet form in conjunction with thermoplastic forming techniques according to an embodiment of the present invention. FIG. 9B illustrates the fabrication of a wave gear device component using BMG-based materials in sheet form in conjunction with thermoplastic forming techniques according to an embodiment of the present invention. FIG. 9C illustrates the fabrication of a wave gear device component using BMG-based material in sheet form in conjunction with thermoplastic forming techniques according to an embodiment of the present invention. FIG. 10A illustrates the fabrication of wave gear drive components using spin forming techniques according to an embodiment of the present invention. FIG. 10B illustrates the fabrication of wave gear drive components using spin forming techniques according to embodiments of the present invention. FIG. 10C illustrates the creation of wave gear drive components using spin forming techniques according to an embodiment of the present invention. FIG. 11A illustrates the fabrication of wave gear drive components using blow molding techniques according to an embodiment of the present invention. FIG. 11B illustrates the fabrication of wave gear drive components using blow molding techniques according to an embodiment of the present invention. FIG. 11C illustrates the fabrication of wave gear drive components using blow molding techniques according to an embodiment of the present invention. FIG. 12A illustrates the formation of wave gearing components using centrifugal casting, according to an embodiment of the present invention. FIG. 12B illustrates the formation of wave gearing components using centrifugal casting, according to an embodiment of the present invention. FIG. 13A illustrates the formation of wave gearing components by thermoplastically forming BMG-shaped material in powder form, according to an embodiment of the present invention. FIG. 13B illustrates the formation of wave gearing components by thermoplastically forming BMG-shaped material in powder form, according to an embodiment of the present invention. FIG. 13C illustrates the formation of wave gearing components by thermoplastically forming BMG-shaped material in powder form, in accordance with an embodiment of the present invention. FIG. 8 illustrates the implementation of gear teeth on a BMG-based wave gearing component using twin roll forming techniques according to embodiments of the present invention. FIG. 15A illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15B illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15C illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15D illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15E illustrates the formation of a flexspline based on the process outlined in FIG. 14 according to an embodiment of the present invention. FIG. 15F illustrates the formation of a flexspline according to the process outlined in FIG. 14 according to an embodiment of the present invention. The fabrication of a wave gear drive component according to embodiments of the present invention shows that the casting process is well controlled. Fig. 6 illustrates that wave gear drive components according to embodiments of the present invention can be made at any suitable scale. FIG. 18A shows the creation of a circular spline according to an embodiment of the present invention. FIG. 18B shows the creation of a circular spline according to an embodiment of the present invention. 6 illustrates the cost benefit of casting or thermoforming wave gearing components from BMG-based materials according to embodiments of the present invention. Shown is a steel-based flexspline.

Referring to the drawings, systems and methods embodying bulk metal glass based wave gearing and wave gearing components are shown. In many embodiments, at least one of the wave generating device, the flexspline, and the circular spline in the corresponding wave gear device comprises a bulk metallic glass based material. In many embodiments, at least the flexspline comprises a bulk metallic glass based material. In many embodiments, the wave generating device, the flexspline, and the circular spline each include a bulk metallic glass based material.

Metallic glasses, also known as amorphous alloys (or alternatively amorphous metals), are characterized by an irregular atomic scale structure whatever their metal component elements,
That is, while ordinary metallic materials generally have a highly regular structure, metallic glass materials are characterized by an irregular atomic structure. In particular, metallic glasses generally have many useful metallic properties, which can be embodied as highly effective engineering materials. For example, metallic glasses are generally much harder than conventional metals and are generally tougher than ceramic materials. They are also relatively resistant to corrosion and, unlike conventional glasses, can have high electrical conductivity. Importantly, the production of metallic glass material itself is suitable for relatively simple processing. In particular, the production of metallic glass can be adapted to an injection molding process or any similar cast molding process.

Nevertheless, the production of metallic glass has challenges that limit its feasibility as an engineering material. In particular, metallic glass generally heats the metallic alloy above its melting point and rapidly cools the melt to solidify so as to avoid its crystallization, thereby forming the metallic glass. The metallic glass in the initial stage requires a drastic cooling rate, for example of the order of 10 ⁶ K / s, which also limits the thickness that can be formed. In fact, due to this thickness limit, metallic glass was initially limited to coating applications.
However, later, special alloy compositions that are more resistant to crystallization were developed, which made it possible to form metallic glass with a rather slow cooling rate, and thus to be made quite thick (for example, , Thicker than 1 mm). These thicker metallic glasses are known as "bulk metallic glasses"("BMGs").

In addition to the development of BMG, “Bulk metallic glass matrix composites” (BMGMCs)
Was also developed. BMGMCs have the characteristic that they have the amorphous structure of BMGs, but also contain the crystalline phase of the material within the amorphous structural matrix. For example, the crystalline phase can be present in dendritic form. The crystalline phase allows the material to have high ductility as compared to a material composed entirely of an amorphous structure.

Even with these developments, the current technology has not yet fully evaluated the beneficial material properties of BMG-based materials (throughout this specification, the term "BMG-based materials, unless otherwise noted, B
It is meant to include MGs and BMGMCs). As a result, BMG-based materials have limited use in engineering applications. For example, various publications have been concluded and largely demonstrated that the feasibility of BMG-based materials is nearly limited to micro-scale structures (see, eg, G. Kumar et al. , Adv. Mater. 2011, 23, 461-476), and Non-Patent Document 2 (M. Ashby et al., Scripta Materialia 54 (2006) 321-326), the disclosures of which are incorporated herein by reference. Shall be incorporated). This is, in part,
This is because the material properties of the BMG-based material including fracture mechanics correlate with the sample size. For example, B
It has been observed that the ductility of the MG material is inversely correlated with its thickness (eg, Non-Patent Document 3 (
Conner, Journal of Applied Physics, Volume 94, Number 2, July 15, 2003, pgs. 904
-911) See, the disclosure of which is incorporated herein by reference). Importantly, as component dimensions increase, they become more susceptible to brittle fracture. Thus, for these or other reasons, one of ordinary skill in the art would generally advise
BMG-based materials can be excellent materials for micro-scale structures such as MEMS devices, but generally advise that they should not be used for macro-scale components (
For example, see Non-Patent Document 1 (G. Kumar et al., Adv. Mater. 2011, 23, 461-476). In fact, G. Kumar et al. Relate brittle fracture to plastic area size, with about one plastic area radius
It was summarized that a sample thickness of 0 times could show a bending plasticity of 5%. Therefore, G. Ku
Mar et al. concluded that Vitreloy's 1 mm thick sample can exhibit a 5% flexural plasticity.

According to the conventional understanding, while suggesting that the application of BMG-based materials is limited, BMG
It is also known that the wear resistance of base materials (for example, Non-Patent Document 4 (Wu, Trans. Nonferrous Me)
T. Soc. China 22 (2012), 585-589; Wu, Intermetallics 25 (2012) 115-125), Non-Patent Document 5 (Kong, Tribal Lett (2009) 35: 151-158; Zenebe, Tribol Lett (2012) 47: 131-1
38), Non-Patent Document 6 (Chen, J. Mater. Res., Vol. 26, No. 20, Oct 28, 2011; Liu, Tr
ibol Lett (2012) 46: 131-138), which disclosures are incorporated herein by reference). For the sake of clarity, "wear" usually refers to the displacement of the material surface as a direct result of mechanical interaction with other materials. In general, it is understood that the resistance of a material to abrasion generally increases with its hardness, ie the harder the material, the less susceptible to abrasion (see, for example, Non Patent Literature 7 (IL Singer, Wea
r, Volume 195, Issues 1-2, July 1996, Pages 7-20)). Based on these understandings, according to the expected wear properties of BMGs, the gears are subjected to a wide range of mechanical interactions, which are subject to wear, making them excellent candidates for materials for making small gears. It has been suggested that it can be mentioned (for example, Non Patent Literature 8 (Chen, J. Mater. Res., Vol. 26, N)
o. 20, Oct 28, 2011), Non-Patent Document 9 (Huang, Intermetallics 19 (2011) 1385-1389)
Non-Patent Document 10 (Liu, Tribol Lett (2009) 33: 205-210), Non-Patent Document 11 (Zhang, M
aterials Science and Engineering A, 475 (2008) 124-127), Non-Patent Document 12 (Ishida)
, Materials Science and Engineering A, 449-451 (2007) 149-154), the disclosures of which are incorporated herein by reference). Thus, in accordance with the above-mentioned insight, micro-scale gears have been made (see Non-Patent Document 12; this disclosure is incorporated herein by reference).

However, contrary to the conventional insight described above, Hofmann et al. Demonstrated that BMG-based materials can be beneficially embodied in a variety of other applications. For example, Patent Document 1 (Hofmann
U.S. Pat. No. 13 / 928,109) discloses a BM for producing gears on a macro scale.
It discloses a method of how to develop G-based materials. In particular, Patent Document 1 describes Ish
While ida demonstrated the fabrication of BMG-based gears, the demonstration showed that the fabricated gears were small in size (and thereby not subjected to the same mode of failure as a macro sized engineering component), It is also described that the gears were limited as long as they were operated using a lubricating oil that could reduce the tendency for brittle fracture. In general, Hofmann et al., The prior art is primarily concerned with exploiting the wear resistance properties of BMG-based materials, and as a result, focuses on achieving the hardest BMG-based materials.
And explained. This design approach is limited as long as the hardest material is susceptible to other failure modes. In fact, Hofmann et al. Demonstrate that the hardest BMG-based materials in the fabrication of macro-scale gears generally produce gears that break during operation. Thus, Hofmann et al. Disclose that BMG-based materials can be developed to have advantageous properties with respect to fracture toughness and thereby allow the creation of macro-scale gears that do not necessarily require a lubricating oil to function. ing. U.S. Pat. No. 5,958,015 is incorporated herein by reference. In addition, US Pat. No. 13 / 942,932 to Hofmann et al. Describes that BMG-based materials have other advantageous material properties, thereby using them to create macro-scale compliance mechanisms. It discloses what can be done. The disclosure of Patent Document 2 is incorporated herein by reference.

Despite this background, it is clear that the versatility of BMG-based materials has not been fully evaluated. This specification discloses how BMG-based materials can be developed and thereby incorporated into wave gearing and wave gearing components. For example, BMG-based materials can be developed to have high fatigue durability, high fracture toughness, excellent sliding friction properties, low density, and high elasticity. Thus, when developed to have these properties, BMG-based materials
Preferably, it can be embodied in the production of the components of the wave gear device, and thereby be embodied in many aspects of the operation of the wave gear device. For example, wave gear devices incorporating BMG-based materials can withstand greater operating loads, can be lighter, and can have a longer service life. Furthermore, BMG-based materials can be cast or thermoplastically formed to the desired geometry (geometrical surface shape), so they can be cast or thermoplastically formed into the shape of wave gear device components can do. In this way, expensive machining processes ubiquitous in the manufacture of steel-based wave gearing and wave gearing components can be reduced, if not eliminated. In summary, wave gearing and wave gearing components incorporating BMG-based materials can provide significantly improved performance at lower cost. The general operation of the wave gearing is described in detail below.

Wave Gearing Operation In many embodiments of the present invention, the wave gearing and wave gearing components are:
BMG based materials are incorporated and provided, thereby having improved performance characteristics. To explain the background, we outline the basic operating principles of wave gearing.

FIG. 1 shows an exploded view of a representative wave gearing that can be made from BMG-based materials, according to an embodiment of the present invention. In particular, the wave gear device 100 includes a wave generator (wave generator) 102, a flexspline (flex spline) 108, and a circular spline (circular spline) 112. The illustrated wave generator 102 comprises a wave generator plug 104 and a ball bearing 106. Importantly, the wave generator plug 104 is oval shaped and disposed within the ball bearing 106 to allow the ball bearing 106 to conform to the oval shape. In this configuration, the outer race of the ball bearing 106 is a wave generator plug 10
It can rotate relative to four. In the illustrated embodiment, the flexspline 108 is shown as cup-shaped, and in particular, the outer peripheral edge of the cup comprises a set of gear teeth 110 in series. In the figure, the flexspline is mounted on a ball bearing so that the outer periphery of the flexspline can conform to the oval shape described above. It should be noted that in this embodiment the ball bearings allow the flexspline to rotate relative to the wave generator plug. The circular splines 112 are ring shaped and, importantly, the inner ring circumference has a series of gear tooth sets. Generally, circular splines 114 have more gear teeth than flexspline gear teeth 110. In many embodiments, circular splines 112 have two more gear teeth than flex splines 108. Generally, the flexspline 108
It fits within the circular splines 112 such that the flexspline gear teeth 110 mesh with the gear teeth of the circular splines 114. In particular, gear teeth 11 of flexspline
Since 0 conforms to an elliptical shape, only gear teeth close to the major axis of the oval engage the gear teeth of the circular spline 114 in the normal case. Conversely, the flexspline gear teeth 110 close to the elliptical short axis disengage from the gear teeth of the circular splines 114. In many embodiments,
Thirty percent of the flexspline gear teeth 110 engage the gear teeth of the circular splines 114. In this configuration, the wave generator plug 104 can rotate in a first direction about the elliptical central axis, thereby causing the flexspline 108 to rotate in a second opposite direction at different rotational speeds about the elliptical central axis. It can be rotated (generally more slowly). This is
The flexspline 108 may be achieved by forming it from a flexible material that can accommodate the deflection resulting from the rotation of the wave generator plug 114.

2A-2D show the normal operation of a wave gear device according to an embodiment of the invention, which can be made from BMG-based materials. In particular, FIG. 2A shows a wave gearing, in which the wave generator plug 204 is in a first orientation with the major axis of the oval perpendicular to the drawing. This start position is designated as "0 °". Arrows 216 designate one of the gear teeth of flexspline 208 to be considered in FIGS. 2A-2D for illustration purposes. FIG. 2B shows that the wave generator plug 204 has rotated 90 ° clockwise. The rotation of the wave generator plug 204 causes the flexspline 208 to be biased in a particular manner such that the gear teeth corresponding to the arrow 216 disengage from the gear teeth of the circular spline 214. In particular, the gear teeth corresponding to arrow 216 are slightly counterclockwise rotated in conjunction with the 90 ° clockwise rotation of wave generator plug 204. In FIG. 2C, the wave generator plug 204 is rotated another 90 ° clockwise and 180 ° clockwise relative to the initial start position. In the figure, arrow 2
The gear teeth designated by 16 re-engage the gear teeth of the circular spline 214 in a slightly counterclockwise position relative to the initial start position. FIG. 4D shows that the wave generator plug 204 has rotated completely 360 degrees clockwise relative to the initial start position. As a result, 216
The gear teeth indicated by are rotated further counterclockwise than the position shown in FIG. 2C. Overall, it can be seen in FIGS. 2A-2D that a full 360 ° rotation in one direction of the wave generator plug 204 results in a slight reverse rotation of the flexspline 208. In this way, the wave gearing can achieve a relatively high reduction ratio within a small footprint. Generally, the input torque is applied to the wave generator plug 204,
The flexspline 208 generates a corresponding output torque.

Of course, although examples of wave gear drive designs have been shown and described, it should be understood that any suitable wave gear drive design and wave gear drive component can be made from BMG-based materials in accordance with embodiments of the present invention. For example, the flexspline can have any suitable shape and need not be "cup-shaped". Similarly, any type of bearing can be implemented rather than a ball bearing. For example, needle roller bearings can be implemented. Specifically, the present application is not intended to be limited to any particular wave gearing design or wave gearing component design. The following is a detailed description of how BMG-based materials can be embodied in wave gearing components to improve the performance of the wave gearing according to the invention.

BMG-Based Wave Gearing and Wave-Gearing Component In many embodiments of the present invention, BMG-based materials are incorporated into a wave-gearing and / or wave-gearing component. In many embodiments, BMG-based materials are developed to be able to have desired material properties that are well suited to the fabrication of wave gear device components. For example, from the above-described principle of operation of the wave gear device, it is understood that the ball bearings and the flexspline are periodically offset by the rotation of the wave generator plug. As a result, those components are desirably made of materials having high fatigue strength. For example,
FIG. 3 shows how the flexspline's fatigue strength can be a major determinant of wave gear device life. In particular, it is common for a flexspline in a wave gear arrangement to fail when the flexspline is fatigued to cause permanent deformation (as opposed to other failure modes).

In general, the fatigue limit of a material is defined by the number of times that a particular level of stress can be applied to the material before the material permanently deforms. Assuming that the same cyclical cyclic loading is applied many times, the lower the loading, the longer the material lasts for a long time before deformation.
The cycle load that a material can withstand for 10 ⁷ cycles is generally referred to as the material's fatigue limit. If the material is subjected to a cyclic load at its yield strength, it is expected to break in the cycle. Thus, the fatigue limit is generally reported as a percentage of the yield strength (normalizing their performance). As shown, 300 M steel has a fatigue limit that is 20% of its yield strength. Incorporating more flexible material reduces the stress per cycle, resulting in fatigue life, assuming that parts of constant geometry (surface shape) as in flexspline are fatigued. Can be quite long.

Thus, BMG-based materials can preferably be incorporated into the flexspline of a wave gearing to provide improved fatigue performance. For example, BMG-based materials can have an elastic limit of as much as 2%, and can be about three times less rigid than steel-based materials. In general, this means that flexsplines made of BMG-based materials can be subjected to lower stresses per deformation unit as compared to steel-based flexsplines having the same geometry. Accordingly, BMG-based materials can have even more favorable fatigue properties, for example, less stressed materials tend to be able to withstand more load cycles. Furthermore, it should be noted that different stiffness values affect the geometry of the component produced. Thus, BMG-based materials can have relatively low stiffness values (e.g., as compared to steel), which can make the wave gearing components a more desirable geometry. For example, relatively low stiffness allows for the realization of thicker flexsplines, which is advantageous. In fact, the material property profile of BMG-based materials in general allows the development of more favorable geometries, ie in addition to stiffness, other material properties of BMG-based materials can also contribute to the development of advantageous geometries .

Furthermore, as can be appreciated from the prior art, BMG-based materials can have higher hardness values, and accordingly demonstrate improved wear performance as compared to existing engineering materials. Materials with high hardness values are particularly advantageous in wave gear systems, ie, because the components of the wave gear system are in continuous contact with one another and, for example, are subjected to sliding friction. Generally, when the gear teeth are subjected to constant load and associated friction,
The resulting associated elastic deformation and wear can cause "ratcheting" prematurely. BMG based materials can have high hardness value, good wear resistance (including good abrasion resistance), and high elasticity, which can even when under high load, wave gearing It can be more suitable to be embodied within. For example, if the BMG material is embodied in the gear teeth of the wave gear device, ratcheting can be suppressed. Furthermore, BMG-based materials can be formed to have high hardness values over a wide temperature range. For example, BMG-based materials can have hardness values that do not change by more than 20% as a function of temperature within a temperature range of 100K-300K. In fact, BMG
The base material can have a strength that does not change by more than 20% as a function of temperature within the temperature range of 100K-300K. In general, it may be desirable at various levels to embody BMG-based materials in wave gearing. Table 1 shows the material properties of certain BMG-based materials:
It shows how to have improved material properties in many respects compared to existing engineering materials.

Importantly, the material properties of BMG-based materials are a function of the relative proportions of the constituent components, and also a function of the crystal structure. As a result, the material properties of the BMG-based material can be tuned by changing the composition and also by changing the ratio of crystal structure to amorphous structure. For example, in many embodiments, it may be desirable to embody BMG-based materials having particular material profiles within particular wave gearing components. In these examples, suitable BMG-based materials can be developed and / or selected to make each wave gearing component among those developed. Table 2,
3 and 4 show how the material properties of the BMG-based material change based on the composition and crystal structure.

FIG. 5 shows how the hardness of the titanium BMG-based material varies with the composition of the alloy. In general, titanium BMG-based alloys tend to have many properties, which make them particularly well suited for making wave gearing and wave gearing components.

Tables 5 and 6 below show how the fatigue properties of BMG based materials change as a function of composition.

Although the data in Tables 5 and 6 are presented, one of the inventors herein performed an independent fatigue test, which is somewhat inconsistent with the data values shown. 4A and 4B are:
The test results conducted are shown.

In particular, FIG. 4A shows monolithic Vitreloy 1, composite LM2, composite DH3, 300-M.
The fatigue resistance of steel, 2090-T81-aluminium, and glass ribbons is shown. These results demonstrate that the composite material DH3 exhibits high resistance to fatigue failure. For example,
Composite DH3 shows that it can withstand about 20,000,000 cycles with a stress amplitude / tensile strength ratio of about 0.25. It should be noted that the monolithic Vitreloy 1 exhibits relatively low resistance to fatigue failure, which appears to be inconsistent with the results shown in Tables 5 and 6. This difference may be due in part to the stringency of obtaining the data. In particular, since the inventor of the present invention understands that critical material properties determine whether fatigue resistance is appropriate for various applications, the inventor has obtained fatigue resistance data obtained under the most severe test conditions. I won. FIG. 4A is a reproduction from Non-Patent Document 13 (Launey, PNAS, Vol. 106, No. 13, 4986-4991), the disclosure of which is incorporated herein by reference.
One of the present inventors is listed as co-author).

Similarly, FIG. 4B shows DV1 ("silver boat", ie manufactured using semi-solid processing)
, DV1 (“Indus”, manufactured using industry standard procedures), composite DH3, composite LM2, monolithic Vitreloy 1, 300-M steel, 2090-T81 aluminum,
And Ti-6Al-4V bimodal fatigue resistance. These results show that the composite material DV1 (
Silver boats have been shown to exhibit even greater resistance to fatigue failure than composite DH3. It should be noted that the results of testing of composite DV1 vary largely based on how composite DV1 was manufactured. When manufactured using “silver boat” technology (“silver boat” refers to semi-solid manufacturing technology, see Non-Patent Document 14 (Hofmann, JOM, Vol. 61,
No. 12, 11-17), the disclosure of which is incorporated herein by reference), which is comparable to fatigue when compared to when manufactured using industry standard techniques. It showed excellent resistance. This difference is due to the fact that the inventor of the present invention does not impose the type of stringency required to produce a sufficiently pure material to the industry standard manufacturing process, and this also causes fatigue failure. It is an enabling factor of the industry that does not recognize how important material composition is in determining material properties, including resistance to FIG. 4B is jointly created by Mr. Launey, together with the results in FIG. 4A, but FIG. 4B is not published in the cited reference above.

In general, FIGS. 4A and 4B show that BMG-based materials can be developed to have better fatigue properties than steel and other existing engineering materials. Importantly, FIGS. 4A and 4B show relative stress amplitude ratios, and BMG-based materials are formed to have a maximum tensile strength better than many steels, as can be extracted from Table 1 be able to. Thus, BMG-based materials can be formed to withstand more load cycles at higher stress levels than some steels. Furthermore, BMG-based materials can be formed to be less rigid, so they can be formed to receive less stress per unit deflection, which results in even better fatigue performance .

From the above description, it is clear that BMG-based materials can have advantageous material properties, which can make them very well suited to be embodied in wave gear device components. Any of the listed BMG-based materials can be embodied in a wave gearing component in accordance with an embodiment of the present invention. More generally, B
The MG-based material can be tailored (eg, via alloying and / or heat treatment) to obtain a material having a desired material profile to be embodied in a wave gear device according to embodiments of the present invention. In general, the desired material property profile can be determined for each wave gear device component to develop a BMG based material that matches the material property profile,
It can also be embodied.

For example, in many embodiments where a low stiffness material is desired, B in the BMG-based composition
The relative proportions of Si, Al, Cr, Co and / or Fe are reduced. Similarly, in many embodiments where low stiffness materials are desired, the volume fraction of soft, ductile dendrites will be high; or alternatively, beta stable elements such as V, Nb, Ta, Mo, And / or Sn
The amount of In general, in BMG MCs, material stiffness changes according to the mixing rule, for example, the stiffness decreases when relatively many dendrites are present, and the stiffness increases when relatively less dendrites are present. It should be noted that, in general, when altering the stiffness of a BMG-based material, the stiffness can be significantly altered without affecting other properties, such as the elastic strain limit or processability of the BMG-based material. The ability to adjust stiffness without affecting other material properties, or processability, is a major advantage in the design of wave gearing and wave gearing components.

Furthermore, the resistance to fatigue failure can also be adjusted according to embodiments of the present invention, since it is possible to adjust the stiffness of the BMG-based material. The alloying elements used to improve resistance to fatigue failure are largely determined empirically. However, it has been observed that the same processing techniques used to enhance fracture toughness also tend to favorably affect resistance to fatigue failure.

In any case, as is apparent from the above description, the above mentioned and described B
Any of the MG-based materials can be incorporated into wave gearing and wave gearing components in accordance with embodiments of the present invention. More generally, any BMG-based material may also be embodied within wave gearing and wave gearing components in accordance with embodiments of the present invention. For example, in many embodiments, the embodied BMG-based material is Fe, Zr,
Based on Ti, Ni, Hf or Cu (ie each of these elements is present in the material in a greater amount than any other element). In some embodiments, the BMG-based material embodied in the wave gear drive component is a Cu-Zr-Al-X composition, where X is, for example,
Y, Be, Ag, Co, Fe, Cr, C, Si, B, Mo, Ta, Ti, V, Nb, Ni
, P, Zn and Pd are one or more elements. In some embodiments, the BMG-based material embodied in the wave gear device component is a Ni-Zr-Ti-X composition, where X is, for example, Co, Al, Cu, B, P, Si, It is one or more elements of Be and Fe. In many embodiments, the BM embodied in a wave gear component
The G-based material is a Zr-Ti-Be-X composition, and X is, for example, Y, Be, Ag, Co,
It is an element of one or more of Fe, Cr, C, Si, B, Mo, Ta, Ti, V, Nb, Ni, P, Zn and Pd. In some embodiments, the wave gearing component is BMG, which is Ni ₄₀ Zr _28.5 Ti _16.5 Al ₁₀ Cu ₅ (atomic fraction)
Including system materials. In some embodiments, the wave gearing component is (Cu _5
0 Zr ₅₀₎ including a BMG material is _x Al _1~12 Be _1~20 Co _0.5~5. In many embodiments, desired material profiles are determined for certain wave gearing components, and BMG-based materials having desired properties are used to construct the wave gearing components. Because BMG-based materials can have many advantageous features, their implementation in wave gearing components can result in a more robust wave gearing. B
This design approach and fabrication of the MG based wave gearing will be described in detail below.

BMG-Based Wave Gearing and Fabrication of Wave Gearing Components In many embodiments of the present invention, the wave gearing components are fabricated from BMG-based materials using casting or thermoplastic forming techniques. Casting or thermoplastic forming techniques can greatly improve efficiency, and this technique produces wave gearing and wave gearing components. For example, steel-based wave gear drive components are generally machined, and due to the complexity of the components, the cost of machining is quite high. Conversely, the use of casting or thermoplastic forming techniques in the development of wave gear device components can avoid overly expensive machining processes.

A method of making a wave gear assembly component incorporating casting or thermoplastic forming techniques is shown in FIG. The process comprises a step 610 of determining the desired material profile of the component to be produced. For example, when making a flexspline, the component material has a specific stiffness, a specific resistance to fatigue failure, a specific density, a specific resistance to brittle failure, a specific resistance to corrosion, a specific resistance to abrasion It is desirable to have gender, specific levels of glass forming ability, etc. In many embodiments, material cost is also a major consideration (
For example, certain BMG-based materials can be more or less expensive than other BMG-based materials)
. In general, any parameter may be a factor in step 610 of determining the material profile for the component to be produced.

It should be noted that any component in the wave gearing can be made according to embodiments of the present invention. As pointed out above, it is particularly advantageous to form the flexspline and the ball bearing from materials having high resistance to fatigue failure, as they are subject to cyclic deformation. Furthermore, it is also advantageous to form the flexspline and the ball bearings from materials having a very high resistance to wear, that is to say that the components have constant contact and relative to one another during normal operation of the wave gearing. Face movement (flex spline teeth wear, and ball bearings and inner and outer races face wear). In some embodiments, the ball of the ball bearing is made of a BMG-based material, and in this way, the ball of the ball bearing can benefit from the enhanced wear resistance that the BMG-based material can provide.

However, it is clear that any component of the wave gearing can be made from BMG based materials according to embodiments of the present invention. In some embodiments, the circular spline gear teeth are made of BMG based material. Thus, the gear teeth of the circular spline are
It can benefit from the improved wear performance properties that BMG-based materials can exhibit. In some embodiments, circular spline gear teeth made from BMG-based materials are then pressed into different, more rigid materials, eg, barium and titanium, but form circular splines, Keep in mind that it is beneficial for relatively rigid circular splines in supporting the motion of the flexspline and wave generator. Thus, B
MG-based material is embodied in gear teeth of circular spline which can exhibit improved wear performance,
The more rigid material can form the remaining portion of the circular spline that can present enhanced structural support.

In many embodiments, most of the components of the wave gearing are made of the same BMG-based material, and in this way, each wave gearing can have a more uniform coefficient of thermal expansion. In any case, any component of the wave gearing can be made from BMG-based materials according to embodiments of the present invention.

Referring back to FIG. 6, a BMG-based material that satisfies the determined material profile is selected (step 620). Any suitable BMG-based material can be selected, including all of those listed in Tables 1-5 and shown in FIGS. 4A-4B and 5. In many embodiments, BMG-based materials are specifically developed to meet the material profile determined in step 610 and selected in step 620. For example, in many embodiments, certain BMG-based materials are developed (e.g., as detailed above) by alloying in any suitable manner to fine-tune material properties. In many embodiments, BMG-based materials are developed by altering the ratio of crystalline structure to amorphous structure (eg, as detailed above) to fine-tune material properties. Of course, any suitable method of developing a BMG-based material that satisfies the material properties determined in step 610 can be embodied in accordance with an embodiment of the present invention.

The BMG-based material selected in step 620 is, for example, thermoplastically formed into the desired shape (eg, the shape of the component to be made) or formed using casting techniques. The production of gear-type components by casting or thermoplastic techniques from BMG-based materials is not currently widespread, but the inventor of the present invention has demonstrated the feasibility of such techniques for this purpose. For example, FIGS. 7A-7D show a 1-inch radius gear made using a single casting step from BMG-based materials. In particular, FIG. 7A shows a steel mold used for gear formation. Figure 7
B shows the removal of BMGMC material from a steel mold. Figures 7C and 7D show SEM images demonstrating the fidelity of the produced components. In particular, gear teeth were also embodied using this preparation method. In this way, complex and expensive machining of the gear teeth can be avoided (conversely, steel based wave gearing components generally rely on machining in component formation). Thus, in accordance with this teaching, in many embodiments, the BMG-based material is thermoplastically formed or cast into the shape of the constituent components of the wave gearing. In many embodiments, the BMG-based material is thermoplastically formed or cast into the shape of the component including the shape of the gear teeth. Further, it should be noted that any suitable thermoplastic forming or casting techniques can be implemented in accordance with embodiments of the present invention. For example, the component of the wave gear device may be formed by one of the direct casting technology, forging technology, spin forming technology, blow molding technology, centrifugal casting technology, and thermoplastic forming technology using BMG-based powder. it can. As can be appreciated by those skilled in the art, BMG-based materials must be cooled quickly enough to maintain at least some amorphous structures. Of course, it should be noted that the wave gearing components can be formed from BMG-based materials in any suitable manner, including machining, in accordance with embodiments of the present invention.

As an example, FIGS. 8A-8D illustrate direct casting techniques that can be implemented to form wave gear set components in accordance with embodiments of the present invention. In particular, FIG. 8A shows the situation of molten BMG-based material 802 ready to be heated to a molten state, thereby being inserted into mold 804. The mold 804 serves to define the shape of the component to be formed. FIG. 8B shows the situation in which molten BMG-based material 802 is pressed into mold 804. Figure 8C.
Shows the situation where the mold 804 is released after cooling the BMG-based material. FIG. 8D shows the situation of removing any excess flash (protruding part). Thus, wave gear drive components can be made using direct casting techniques in conjunction with BMG based materials in accordance with embodiments of the present invention. It should be noted that the casting of crystalline metals suitable for implementation in wave gear drive components is generally not feasible.

9A-9C illustrate other formation techniques that may be implemented in accordance with embodiments of the present invention. In particular, FIGS. 9A-9C illustrate thermoplastic forming of BMG-based materials in sheet form, in accordance with embodiments of the present invention. In particular, FIG. 9A shows that BMG has been heated to carry out this thermoplastic formation.
A sheet 902 of a base material is shown. In the illustrated embodiment, the sheet 902 of BMG-based material is heated by capacitive discharge techniques, but it should be understood that any suitable heating method may be practiced in accordance with embodiments of the present invention. FIG. 9B shows the situation where a press is used to push the BMG based material into the mold 904 to form the component to be made. FIG. 9C shows the situation where the mold 904 is released to remove any excess flush. In this way, the desired component is obtained.

As mentioned above, heating of the thermoplastically formable BMG-based material can be accomplished in any suitable manner in accordance with embodiments of the present invention. For example, FIGS. 10A-10C show that heating of BMG-based materials in sheet form can be achieved by spinning friction. 10A to 10C are the same as FIG.
It is similar to that found in A-9C, except that it is pressed against the BMG-based material 1002 and frictionally heats the BMG-based sheet material by rotation of the press 1010. In this way, the BMG-based material can be heated to the extent that it can be thermoplastically formed. This technique is referred to as "spin formation".

It should be noted that while the above description relates to mechanically matching the BMG based material to the mold, the BMG based material may be formed in the mold in any suitable manner in accordance with embodiments of the present invention it can. In many embodiments, the BMG-based material is matched to the mold using one of forging techniques, vacuum techniques, drawing techniques, and magnetic forming techniques. of course,
The BMG-based material can be matched to the mold in any suitable manner in accordance with embodiments of the present invention.

11A-11C illustrate the use of blow molding techniques to form portions. In particular, FIG. 11A shows the situation where the BMG-based material is placed in a mold. FIG. 11B shows the BMG material 11
21 shows a situation where B. 02 is exposed to a pressurized gas or liquid to make the BMG-based material conform to the shape of the mold 1104. Generally, pressurized inert gas is used. As is conventional, the BMG-based material is heated as usual to facilitate full shaping and to be affected by pressurized gas or liquid. Again, any suitable heating technique can be implemented in accordance with embodiments of the present invention. FIG. 11C shows that the BMG-based material is a mold 11 due to the force of the pressurized gas or liquid.
Indicates a situation that matches the shape of 04.

Figures 12A and 12B illustrate that centrifugal casting can be performed to form the component components of a wave gearing. FIG. 12A shows a mold 1204 for melting BMG material 1202.
The situation is shown in which the BMG material is made to conform to the shape of the mold by injecting into the inside and rotating the mold.

13A-13C load the BMG-based material in powder form into a mold and then heat it to render the material thermoplastically formable, thereby, according to embodiments of the present invention, the desired component It shows forming in the shape of. In particular, FIG. 13A shows that B in powder form
The situation which deposited MG system material 1302 in the metallic mold is shown. FIG. 13B shows the BMG material 130
2 shows heating and pressing to conform to the shape of the mold 1304. Also, FIG. 13C.
Indicates a situation where the BMG-based material solidifies, thereby forming the desired component.

It will be appreciated that, generally, any technique suitable for thermoplastic forming or casting BMG-based materials can be practiced in accordance with embodiments of the present invention. The above examples are meant to be illustrative and not exhaustive. More generally, any technique suitable for forming wave gearing components comprised of BMG-based materials may be implemented in accordance with embodiments of the present invention.

Referring back to FIG. 6, process 600 further comprises performing 640 optional post-forming operations to finish the fabricated components, if desired. For example, in some embodiments, the overall shape of the flexspline is thermoplasticized or cast and then the gear teeth are machined to the flexspline. In some embodiments,
Apply twin roll forming technology, and provide gear teeth on flexspline or circular spline. Figure 1
4 shows a twin roll forming arrangement which can be used to embody gear teeth in a flexspline.
In particular, the arrangement 1400 supports the movement of the flexspline 1402 by means of this arrangement.
A roller and a second roller 1412 act to define gear teeth in the flexspline. The flexspline 1402 is heated to be more easily shaped and ready to be defined by the second roller. Of course, roll-formed parts can be finished using any suitable technique according to embodiments of the present invention. For example, gear teeth
It can be implemented using conventional machining techniques. In addition, roll-formed parts can be finished (not only to define gear teeth) in any suitable manner according to embodiments of the present invention.

15A-15F illustrate the fabrication of flexsplines in accordance with the process outlined in FIG. FIG. 15A shows the multi-piece mold used to cast the overall shape of the flexspline, and FIG. 15B shows the assembled multi-piece mold used to cast the overall shape of the flexspline, FIG. 15C shows casting of flexspline using BMG-based material, FIG. 15D shows disassembly of mold, FIG. 15E shows flexspline removed from the mold, and FIG. Is machined to indicate that gear teeth can be provided. It should be noted that although the drawings show machining gear teeth into flexsplines, the flexsplines can be cast to have the desired gear teeth. In this way, costly machining can be avoided.

It should be noted that the forming techniques are extremely sensitive with regard to process control. In general, it is beneficial to precisely control fluid flow, venting, temperature and cooling when forming parts.
For example, FIG. 16 shows several attempts at flexspline formation using casting techniques and shows that many attempts are apparently incomplete. In particular, seven samples in the image were made using TiZrCuBe BMG-based material with a density of 5.3 g / cm ³ .
The rightmost sample in the image was made from Vitreloy 1.

FIG. 17 shows the creation of parts of various scales using the process described above.
As an example, FIG. 17 shows a larger flexspline made according to the process described above, as well as a smaller flexspline made according to the process described above. Thus, the process described above is versatile.

It should be understood that FIGS. 15-17 relate to the fabrication of a flexspline, but any wave gearing component can be made from BMG-based materials in accordance with an embodiment of the present invention. For example, Figures 18A-18B illustrate circular splines made from BMG-based materials. In particular, FIG. 18A shows a titanium BMG based material fabricated with 1.5 inch circular splines, and FIG. 18B shows fabricated circular splines for fabricated flex splines. Although the circular splines are not shown as having gear teeth, the gear teeth can then be machined into circular splines.

The fabrication techniques described above can be used to efficiently fabricate wave gearing and wave gearing components. For example, as pointed out earlier in the above description, the costs associated with component machining can be avoided using these techniques. Thus, the cost of making certain wave gearing components is mainly a function of the raw material cost, which is true regardless of the size of the components. Conversely, when forming a steel-based wave gear drive component, the cost of manufacturing that component increases with size reductions that exceed some critical value. This is because it becomes difficult to machine smaller sized parts.

As an example, FIG. 19 shows the relationship for flexsplines that the raw material cost of amorphous metal is higher than that of steel. For example, the stiffness of the steel may require the flexspline to have a diameter smaller than some specified amount, for example 50.8 mm (2 inches), and may need to have a wall thickness smaller than some amount, for example 1 mm. To illustrate the situation, FIG. 20 shows a steel-based flexspline having a diameter of 50.8 mm (2 inches) and a wall thickness of 0.8 mm. Importantly, when the flexspline is made smaller, for example less than 1 inch in diameter, the steel wall is too thin to be easy to machine. As a result, even when the cost of the amorphous metal source is higher than that of steel, the flexspline can be made cheaper by manufacturing from amorphous metal. In short, time-consuming machining can be eliminated by casting parts from BMG-based materials,
Also, the cost of the flexspline can be reduced accordingly.

As can be inferred from the above description, the above concepts can be embodied in various configurations in accordance with embodiments of the present invention. For example, in some embodiments, wave gear device components are cast molded from a polymeric material and then coated with a bulk metallic glass based material. In this way, the wear resistance properties of bulk metallic glass-based materials can be exploited. Thus, while the present invention has been described in particular embodiments, many additional variations and modifications will be apparent to those skilled in the art. Thus, it should be understood that the present invention can be practiced other than as specifically described herein. Accordingly, the embodiments of the present invention should be considered in all respects as illustrative and not restrictive.

U.S. Patent No. 13/928109 U.S. Patent No. 13/942 932

G. Kumar et al., Adv. Mater. 2011, 23, 461-476 M. Ashby et al., Scripta Materialia 54 (2006) 321-326 Conner, Journal of Applied Physics, Volume 94, Number 2, July 15, 2003, pgs. 904-911 Nonferrous Met. Soc. China 22 (2012), 585-589; Wu, Intermetallics 25 (2012) 115-125) Kong, Tribal Lett (2009) 35: 151-158; Zenebe, Tribol Lett (2012) 47: 131-138 Chen, J. Mater. Res., Vol. 26, No. 20, Oct 28, 2011; Liu, Tribol Lett (2012) 46: 131-138 I. L. Singer, Wear, Volume 195, Issues 1-2, July 1996, Pages 7-20 Chen, J. Mater. Res., Vol. 26, No. 20, Oct 28, 2011 Huang, Intermetallics 19 (2011) 1385-1389 Liu, Tribol Lett (2009) 33: 205-210 Zhang, Materials Science and Engineering A, 475 (2008) 124-127 Ishida, Materials Science and Engineering A, 449-451 (2007) 149-154 Launey, PNAS, Vol. 106, No. 13, 4986-4991 Hofmann, JOM, Vol. 61, No. 12, 11-17

Claims (20)

A wave generator,
A flexspline with a first set of gear teeth,
A circular spline with a second set of gear teeth,
Equipped with
A wave gear device, wherein at least one of the wave generator, the flexspline, and the circular spline includes a bulk metallic glass based material. The wave gear device according to claim 1, wherein the wave generator comprises a wave generator plug and a bearing.   A wave gearing according to claim 2, wherein the bearing is a ball bearing. The wave gearing according to claim 1, wherein each of the wave generating device, the flexspline and the circular spline comprises a bulk metallic glass based material. A wave gearing according to claim 1, wherein at least one of the first set of gear teeth and the second set of gear teeth comprises bulk metallic glass based material. A wave gearing according to claim 1, wherein each of said first set of gear teeth and said second set of gear teeth comprises bulk metallic glass based material. A wave gearing according to claim 6, wherein the wave generating device comprises a ball bearing comprising a bulk metallic glass based material. The wave gear device according to claim 1, wherein the element of the bulk metallic glass based material present in the largest amount is one of Fe, Zr, Ti, Ni, Hf and Cu. The wave gear device according to claim 1, wherein the bulk metallic glass based material is Ni ₄₀ Zr.
_28.5 Ti _16.5 Al ₁₀ Cu ₅ wave gear device. A wave generator plug having an elliptical cross section;
A bearing having an inner race, an outer race and a plurality of rolling members;
Equipped with
The wave generator plug is disposed within the bearing so that the bearing can conform to the elliptical shape of the wave generator plug;
A wave generating device, wherein at least one of the wave generating device plug and the bearing comprises a bulk metallic glass based material.   A wave generating device according to claim 10, wherein the bearing is a ball bearing. A flexspline comprising a flexible body defining a circular shape, the outer periphery of the circular shape defining a set of gear teeth, the flexible body comprising a bulk metallic glass based material. The flexspline of claim 12, wherein the set of gear teeth comprises a bulk metallic glass based material. A circular spline comprising a ring-like body, the inner circumference of said ring-like body defining a set of gear teeth, said ring-like body comprising a bulk metallic glass based material. The circular spline of claim 14, wherein the set of gear teeth comprises a bulk metallic glass based material. A method of making a wave gear drive component, comprising:
Molding the BMG-based material using a mold associated with one of the thermoplastic forming and casting techniques;
The BMG-based material may be a wave generator plug, an inner race, an outer race, a rolling element, a flexspline, a flexspline without a set of gear teeth, a circular spline, a circular spline without a set of gear teeth A set of gear tooth sets to be incorporated into the flexspline, and a method formed as one of a set of gear tooth sets to be incorporated into the circular spline. 17. The method of claim 16, further comprising the step of machining the BMG-based material after forming by either thermoplastic forming or casting techniques. 18. The method of claim 17, wherein the BMG-based material is shaped as one of a flexspline without a set of gear teeth and a circular spline without a set of gear teeth, the gear teeth being A method for machining BMG-based materials. 19. The method of claim 18, wherein the BMG-based material is shaped as one of a flexspline without a set of gear teeth and a circular spline without a set of gear teeth, the gear teeth being A method embodied for a BMG-based material using a twin roll forming technique. 17. The method of claim 16, wherein the BMG-based material is molded using one of direct casting technology, blow molding technology, and centrifugal casting technology.