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 (about 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 nature of the tooth geometry Globoid pinion can mesh not merely with the mating enveloping gear but also with a properly designed cylindrical helical gear. Using a helical equipment with a Globoid pinion is certainly common in lower cost in applications such as for example automotive electric powered equipment actuators. The significant cost advantage comes due to the possibility to injection mold the helical plastic gear. The load capacity of the simplified helical/Globoid transmitting is decreased to the particular level below the load capacity of the regular worm gear. However the driving efficiency continues to be better evaluate to the regular worm gear.
There are only 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 can be understood that the apparatus is produced by CNC milling with make use of a small ball shaped cutter.
Ever-power has capacity to design, prototype and offer Globoid gear items. The expertise of Ever-power is 3-dimentional simulation and modeling of the Globoid and double 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 significantly reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It has to be noted that production of the Globoid gear is more complex compare to production of the Globoid pinion. The Globoid pinion can be produced in high quantities by turning, whirling or grinding. During the machining process of the Globoid pinion the reducing tool needs to be capable to tilt to be able to produce the enveloping form.
The newer production methods are under development. The most promising creation method of the Globoid pinion is certainly continues grinding procedure, which incorporates a grinding wheel (diamond or CBN plated) with particular Ever-power simulated geometry. The complication of the novel process is the difficulties with simulation of the geometry of the grinding device. The grinding tooth would have to globoid worm generate a correct type of the Globoid pinion without tilting therefore the production price and the production price would be considerably reduced. Ever-power has developed a computer based device for creating of 3-dimensional CAD types of grinding tools for high volume creation of the Globoid products.
The most common usage of the Globoid gear set was noticed 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 generating the trimming 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
Bishop
Ever-power
Vr-rack technology was introduced:
Before 2000
2000
Underlying mathematical model is founded on:
Classic
gear
theory
Direct
Digital
Simulation
Rack geometry calculation accuracy is:
Limited by the boundaries of the classic gear theory
Unlimited
Capability to produce the vr-rack with not involute type for reduced noise
NO
YES
Capability to generate vr-rack with an increase of ratio gain is:
Limited
YES
Cost of vr-rack style is:
High
Low
Ever-power advanced Variable Ratio rack and pinion high ratio gain technology for motor sport racing applications.
Ever-power low sound Variable Ratio rack and pinion not involute technology.
Ever-power pioneered in developing of the next generation of Globoid gears. In 1999 Ever-power released a skew axis Globoid gear as a higher load capacity and increased driving effectiveness alternative to the classic Globoid equipment.
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 first in proposing this design and, moreover, he was the first who produces an accurate working model of the apparatus in 3-dimantional CAD system. The accurate 3-d CAD of the WORMOID equipment has proved the capability of the concept such as for example conjugated transmission actions and significant boost of number of tooth 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 style and development of products based on Ever-power wormoid technology.
It needs to be noted that wormoid equipment design 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 one’s teeth in the mesh. The apparatus torque is usually carried by more teeth so the load on each individual tooth is reduced. The other obvious advantage is boost driving efficiency. As you can see, the part of the pinion with bigger diameter is driving the corresponding portion of the gear, which has a larger diameter aswell. Such of exclusive feature of Ever-power wormoid can be missing in the traditional Globoid gear and outcomes in higher sliding velocities and higher friction medication on the traditional globoid gear. A skilled in the art engineer would instantly derive possible design advantages of the wormoid gear. For instance, using of the wormoid equipment can significantly reduce cost of electric powered help mechanisms that are commonly applied to modern automobiles. Because of the higher driving efficiency, wormoid equipment set can be designed with increase ration and offer the same driving effectiveness as the initial worm or dual enveloping worm gear. For instance 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 would be capable to increase the ratio up to 30:1 and the torque on the apparatus up to 150 Hm without boost of the center distance between the gear and the pinion.