ypical Globoid gear.
Globoid (or Double Enveloping Worm or Hour Glass) gear has advantage versus a globoid worm traditional worm gear due to increased driving efficiency ( 6-10% higher on 25:1 ratio) and increased loading capacity (about 30%).
The disadvantage of a globoid gear is higher manufacturing cost and sensitivity of the enveloping pinion to the axial location.
Because of the geometrical character of the tooth geometry Globoid pinion can mesh not only with the mating enveloping equipment but also with a properly designed cylindrical helical equipment. Using a helical equipment with a Globoid pinion is usually common in lower cost in applications such as for example automotive electric powered equipment actuators. The significant price advantage comes due to the possibility to injection mold the helical plastic material gear. The load capability of the simplified helical/Globoid transmission is decreased to the particular level below the load capacity of the standard worm gear. Nevertheless the driving efficiency continues to be better evaluate to the standard worm gear.
There are simply a few suppliers of the Globoid gear. division of Textron, located in Traverse City, MI. The detailed details about processes used at Cone Drive for manufacturing of its gear cannot be found. However, predicated on publicly released details it could be understood that the gear is manufactured by CNC milling with use a little ball shaped cutter.
Ever-power has capacity to design, prototype and offer Globoid gear items. The experience 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 making globoid gear at significantly reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It has to be noted that production of the Globoid equipment is more complex compare to production of the Globoid pinion. The Globoid pinion can be produced in high amounts by turning, whirling or grinding. During 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 advancement. The most promising production approach to the Globoid pinion is normally continues grinding process, which incorporates a grinding wheel (gemstone or CBN plated) with particular Ever-power simulated geometry. The complication of the novel procedure is the difficulties with simulation of the geometry of the grinding tool. The grinding tooth would need to generate a correct type of the Globoid pinion without tilting so the production rate and the production price would be considerably reduced. Ever-power has developed a computer based tool for producing of 3-dimensional CAD types of grinding equipment for high volume creation of the Globoid items.
The most common usage 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 already been made by grinding with a tilting grinding wheel. The Globoid gears have been cut by a particular hub, which replicated the form of the Globoid Pinion. Special machines for making the slicing hubs have already been developed. As the modern automotive steering systems began to use classic Bishop or advanced Ever-power variable 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
Capacity to produce the vr-rack with not involute form for reduced noise
Capacity to generate vr-rack with an increase of ratio gain is:
Cost of vr-rack style is:
Ever-power advanced Adjustable Ratio rack and pinion high ratio gain technology for motor sport racing applications.
Ever-power low noise Variable Ratio rack and pinion not involute technology.
Ever-power pioneered in developing of another generation of Globoid gears. In 1999 Ever-power launched a skew axis Globoid gear as a high load capacity and increased driving performance alternative to the classic Globoid equipment.
Ever-power skew axis (wormoid) gear.
It needs to be noted that the name WORMOID will not relate to any scientific term in fact it is a product of Dr. Stepan V. Lunin, who was the first in proposing this design and, more importantly, he was the 1st who produces a precise functioning model of the gear in 3-dimantional CAD system. The accurate 3-d CAD of the WORMOID gear has proved the ability of the idea such as for example conjugated transmission action and significant increase of number of teeth in the contact 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 products based on Ever-power wormoid technology.
It has to be noted that wormoid gear style from Ever-power is actually promising unique advantages review to the vintage Globoid (double enveloping) equipment. Among the obvious advantages is elevated load capacity due to increased number of the teeth in the mesh. The apparatus torque is definitely carried by even more teeth therefore the load on each individual tooth is reduced. The other apparent advantage is increase 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 a
swell. Such of exclusive feature of Ever-power wormoid is missing in the traditional Globoid gear and outcomes in higher sliding velocities and higher friction drug on the traditional globoid gear. An experienced in the artwork engineer would instantly derive possible design advantages of the wormoid gear. For example, using of the wormoid equipment can significantly reduce cost of electric powered aid mechanisms that are generally used on modern automobiles. Due to the bigger driving efficiency, wormoid equipment set can be made with increase ration and offer the same driving efficiency as the initial worm or dual enveloping worm equipment. For example NSK worm equipment steering actuator with a ration of about 20:1 provides about 80% of driving efficiency. The plastic equipment would hold about 80 Hm of torque. An alternative solution wormoid gear style from Ever-power will be capable to increase the ratio up to 30:1 and the torque on the gear up to 150 Hm without boost of the center distance between the gear and the pinion.
ypical Globoid gear.