ypical Globoid gear.
Globoid (or Double Enveloping Worm or Hour Glass) gear has advantage globoid worm pitched against a traditional worm equipment because of increased driving efficiency ( 6-10% higher about 25:1 ratio) and increased loading capacity (about 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 gear but also with a correctly designed cylindrical helical equipment. Using a helical equipment with a Globoid pinion can be common in reduced cost in applications such as automotive electric powered gear actuators. The significant cost advantage comes due to the likelihood to injection mold the helical plastic gear. The load capacity of the simplified helical/Globoid transmitting is reduced to the level below the load capacity of the regular worm gear. However the driving efficiency is still better evaluate to the regular worm gear.
There are only a few suppliers of the Globoid gear. division of Textron, situated in Traverse City, MI. The detailed information about processes used at Cone Drive for manufacturing of its gear could not be found. However, predicated on publicly released information it can be understood that the apparatus is produced by CNC milling with use a little ball shaped cutter.
Ever-power has capacity to design, prototype and supply 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 gear CAD models can be used in numerous CNC machining shops for producing globoid gear at significantly reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It has 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 amounts by turning, whirling or grinding. Through the machining process of the Globoid pinion the trimming tool needs to be able to tilt to be able to produce the enveloping shape.
The newer production methods are under development. The most promising creation approach to the Globoid pinion is definitely continues grinding procedure, which includes a grinding wheel (gemstone 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 tool. The grinding tooth would need to generate a correct form of the Globoid pinion without tilting so the production rate and the production price would be significantly reduced. Ever-power has developed a computer based tool for generating of 3-dimensional CAD models of grinding tools for high volume creation of the Globoid products.
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 produced 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 reducing hubs have already been developed. As the modern automotive steering systems started to use traditional Bishop or advanced Ever-power adjustable ratio rack and pinion technology, the demand for the Globoid gears has been reduced.
Variable ratio technology comparison
Vr-rack technology was introduced:
Underlying mathematical model is based on:
Rack geometry calculation accuracy is:
Limited by the boundaries of the classic gear theory
Capability to produce the vr-rack with not involute type for reduced noise
Capacity to generate vr-rack with increased ratio gain is:
Cost of vr-rack design is:
Ever-power advanced Adjustable 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 introduced 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 does not relate to any scientific term and it is something of Dr. Stepan V. Lunin, who was the 1st in proposing this style and, more importantly, he was the first who produces a precise operating model of the apparatus in 3-dimantional CAD system. The accurate 3-d CAD of the WORMOID equipment has proved the ability of the idea such as for example conjugated transmission action and significant boost of number of teeth in the contact compare to the classic Globoid gear.
CAD 3-d style of Ever-power wormoid gear.
Ever-power happens to be offering assistance for style and development of items 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 classic Globoid (double enveloping) equipment. Among the obvious advantages is elevated load capacity due to increased number of one’s teeth in the mesh. The apparatus torque can be carried by more teeth therefore the load on each individual tooth is reduced. The other apparent advantage is increase driving efficiency. As you can see, the part of the pinion with bigger diameter is driving the corresponding part of the gear, that includes a larger diameter aswell. Such of unique feature of Ever-power wormoid is normally missing in the classic Globoid gear and outcomes in higher sliding velocities and higher friction drug on the classic 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 commonly used on modern automobiles. Due to the higher driving efficiency, wormoid gear set can be made with increase ration and provide the same driving performance as the original worm or double enveloping worm gear. For example NSK worm equipment steering actuator with a ration around 20:1 provides about 80% of traveling efficiency. The plastic equipment would hold about 80 Hm of torque. An alternative solution wormoid gear design 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 guts distance between the equipment and the pinion.
ypical Globoid gear.