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 in 25:1 ratio) and increased loading capacity (on the subject of 30%).
The disadvantage of a globoid gear is higher production 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 merely with the mating enveloping equipment but also with a correctly designed cylindrical helical gear. Using a helical gear with a Globoid pinion is normally common in reduced cost in applications such as for example automotive electric powered gear actuators. The significant price advantage comes because of the likelihood to injection mold the helical plastic material gear. The load capability of the simplified helical/Globoid transmitting is decreased to the level below the load capacity of the regular worm gear. However the driving efficiency is still better compare 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 procedures utilized at Cone Drive for manufacturing of its gear could not be found. However, based on publicly released information it could be understood that the apparatus is manufactured by CNC milling with use a small ball shaped cutter.
Ever-power has capability to design, prototype and offer Globoid gear products. The knowledge of Ever-power is 3-dimentional globoid worm simulation and modeling of the Globoid and dual enveloping tooth geometry. Ever-power 3-dimentional Globoid and double enveloping equipment CAD models can be used in various CNC machining shops for creating globoid gear at considerably reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It needs to be noted that manufacturing of the Globoid equipment is more complex compare to production of the Globoid pinion. The Globoid pinion could be produced in high quantities by turning, whirling or grinding. During the machining procedure for the Globoid pinion the trimming tool has to be able to tilt in order to produce the enveloping shape.
The newer production methods are under development. The most promising production approach to the Globoid pinion can be continues grinding process, which includes a grinding steering wheel (diamond or CBN plated) with particular Ever-power simulated geometry. The complication of the novel process is the problems with simulation of the geometry of the grinding device. The grinding tooth would have to generate a correct form of the Globoid pinion without tilting so the production price and the production cost would be significantly reduced. Ever-power is rolling out a computer based tool for creating of 3-dimensional CAD types of grinding equipment for high volume creation 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 already been made by grinding with a tilting grinding wheel. The Globoid gears have already been cut by a particular hub, which replicated the shape of the Globoid Pinion. Special machines for creating the cutting hubs have been developed. As the modern motor vehicle steering systems began to use classic Bishop or advanced Ever-power variable ratio rack and pinion technology, the demand for the Globoid gears has been reduced.
Variable ratio technology comparison
Vr-rack technology was introduced:
Before 2000
Underlying mathematical model is based on:
Rack geometry calculation accuracy is:
Limited by the boundaries of the traditional gear theory
Capability to produce the vr-rack with not involute type for reduced noise
Capacity 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 another era of Globoid gears. In 1999 Ever-power presented a skew axis Globoid gear as a higher 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 a product of Dr. Stepan V. Lunin, who was the initial in proposing this design and, moreover, he was the initial who produces an accurate functioning model of the gear in 3-dimantional CAD system. The accurate 3-d CAD of the WORMOID gear has proved the capability of the idea such as conjugated transmission action and significant increase of number of tooth in the get in touch with compare to the traditional Globoid gear.
CAD 3-d model of Ever-power wormoid gear.
Ever-power happens to be offering assistance for style and development of items predicated 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) gear. Among the obvious advantages is elevated load capacity due to increased number of one’s teeth in the mesh. The apparatus torque is carried by even more teeth so the load on every individual tooth is decreased. The other apparent advantage is boost driving efficiency. As one can see, the portion of the pinion with larger diameter is driving the corresponding portion of the gear, which has a larger diameter aswell. Such of exclusive feature of Ever-power wormoid is certainly missing in the traditional Globoid gear and outcomes in higher sliding velocities and higher friction drug on the classic globoid gear. A skilled in the art engineer would instantly derive possible design benefits of the wormoid gear. For instance, using of the wormoid equipment can significantly reduce price of electric powered aid mechanisms that are generally used on modern automobiles. Because of the bigger driving efficiency, wormoid equipment set can be designed with increase ration and offer the same driving efficiency as the initial worm or double enveloping worm gear. For instance NSK worm gear steering actuator with a ration around 20:1 provides about 80% of generating efficiency. The plastic equipment would hold about 80 Hm of torque. An alternative wormoid gear style from Ever-power will be capable to increase the ratio up to 30:1 and the torque on the apparatus up to 150 Hm without increase of the center distance between the equipment and the pinion.