ypical Globoid gear.
Globoid (or Double Enveloping Worm or Hour Glass) gear has advantage pitched against a traditional worm equipment due to increased driving efficiency ( 6-10% higher about 25:1 ratio) and increased loading capacity (on the subject of 30%).
The disadvantage of a globoid gear is higher manufacturing cost and sensitivity of the enveloping pinion to the axial location.
Due to the geometrical character of the tooth geometry Globoid pinion may mesh not only with the mating enveloping equipment but also with a correctly designed cylindrical helical equipment. Using a helical gear with a Globoid pinion can be common in reduced cost in applications such as for example automotive electric powered equipment actuators. The significant price advantage comes due to the likelihood to injection mold the helical plastic gear. The load capability of the simplified helical/Globoid transmission is reduced to the level below the load capacity of the standard worm gear. Nevertheless the driving efficiency is still better compare to the regular worm gear.
There are simply a few suppliers of the Globoid gear. division of Textron, situated in Traverse City, MI. The detailed information about procedures utilized at Cone Drive for manufacturing of its gear could not be found. However, based on publicly released details it could be understood that the apparatus is produced by CNC milling with make use of a little ball shaped cutter.
Ever-power has capacity to design, prototype and offer Globoid gear products. The knowledge of Ever-power is 3-dimentional simulation and modeling of the Globoid and dual enveloping tooth geometry. Ever-power 3-dimentional Globoid and double enveloping equipment CAD versions can be used in various CNC machining shops for creating globoid gear at significantly reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It needs to be noted that manufacturing of the Globoid gear is more technical compare to production of the Globoid pinion. The Globoid pinion can be produced in high amounts by turning, whirling or grinding. Through the machining procedure for the Globoid pinion the cutting tool needs to be able to tilt to be able to produce the enveloping form.
The newer production methods are under development. The most promising production approach to the Globoid pinion is continues grinding process, which incorporates a grinding steering wheel (gemstone or CBN plated) with specific Ever-power simulated geometry. The complication of the novel procedure is the problems with simulation of the geometry of the grinding device. The grinding tooth would have to generate a correct kind of the Globoid pinion without tilting so the production rate and the production cost would be significantly reduced. Ever-power has developed a computer based device for making of 3-dimensional CAD types of grinding tools for high volume production of the Globoid items.
The most common use of the Globoid gear set was seen in 1961-1989 on automotive steering systems in Italy and in Soviet Union.
VAZ-2101 with Globoid steering technology.
The Globoid pinions have been made by grinding with a tilting grinding wheel. The Globoid gears have been cut by a special hub, which replicated the form of the Globoid Pinion. Special machines for making the slicing hubs have been developed. Because the modern automotive steering systems started to use classic Bishop or advanced Ever-power adjustable ratio rack and pinion technology, the demand for the Globoid gears provides been reduced.
Variable ratio technology comparison
Vr-rack technology was introduced:
Underlying mathematical model is founded on:
Rack geometry calculation accuracy is:
Tied to the boundaries of the traditional gear theory
Capability to produce the vr-rack with not involute form for reduced noise
Capability to generate vr-rack with an increase of ratio gain is:
Cost of vr-rack design is:
Ever-power advanced Variable Ratio rack and pinion high ratio gain technology for engine sport racing applications.
Ever-power low noise Variable Ratio rack and pinion not involute technology.
Ever-power pioneered in developing of the next generation of Globoid gears. In 1999 Ever-power launched a skew axis Globoid gear as a high load capacity and increased driving efficiency option to the classic Globoid gear.
Ever-power skew axis (wormoid) gear.
It has to be noted that the name WORMOID will not relate with any scientific term and it is something of Dr. Stepan V. Lunin, who was simply the first in proposing this style and, more importantly, he was the initial who produces a precise operating model of the gear in 3-dimantional CAD system. The accurate 3-d CAD of the WORMOID gear has proved the capability of the concept such as conjugated transmission actions and significant increase of number of tooth in the get in touch with compare to the traditional Globoid gear.
CAD 3-d style of Ever-power wormoid gear.
Ever-power happens to be offering assistance for design and development of items predicated on Ever-power wormoid technology.
It needs to be noted that wormoid gear style from Ever-power is actually promising unique advantages review to the classic Globoid (double enveloping) equipment. Among the obvious advantages is elevated load capacity because of increased number of the teeth in the mesh. The gear torque is definitely carried by more teeth so the load on each individual tooth is reduced. The other obvious advantage is boost driving efficiency. As one can see, the portion of the pinion with larger diameter is traveling the corresponding portion of the gear, which has a larger diameter aswell. Such of unique feature of Ever-power wormoid is normally missing in the traditional Globoid gear and results in higher sliding velocities and higher friction drug on the traditional globoid gear. An experienced in the art engineer would instantly derive possible design benefits of the wormoid gear. For example, using of the wormoid gear can significantly reduce price of electric powered help mechanisms that are generally applied to modern automobiles. Because of the higher driving efficiency, wormoid gear set can be designed with increase ration and provide the same driving performance as the globoid worm original worm or double enveloping worm gear. For instance NSK worm equipment steering actuator with a ration of about 20:1 delivers about 80% of generating efficiency. The plastic equipment would hold about 80 Hm of torque. An alternative solution wormoid gear style from Ever-power would be capable to boost the ratio up to 30:1 and the torque on the apparatus up to 150 Hm without enhance of the guts distance between the gear and the pinion.
ypical Globoid gear.