ypical Globoid gear.
Globoid (or Double Enveloping Worm or Hour Glass) gear has advantage pitched against a traditional worm equipment because of 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 production cost and sensitivity of the enveloping pinion to the axial location.
Because of the geometrical nature of the tooth geometry Globoid pinion may mesh not merely with the mating enveloping gear but also with a properly designed cylindrical helical equipment. Using a helical gear with a Globoid pinion is normally common in reduced cost in applications such as automotive electric powered gear actuators. The significant cost advantage comes because of the likelihood to injection mold the helical plastic material gear. The load capacity of the simplified helical/Globoid transmitting is decreased to the level below the load capacity of the regular worm gear. Nevertheless the driving efficiency is still better evaluate to the standard worm gear.
There are just a few suppliers of the Globoid gear. division of Textron, positioned in Traverse City, MI. The detailed details about procedures used at Cone Drive for manufacturing of its gear cannot be found. However, predicated on publicly released information it could be understood that the apparatus is manufactured by CNC milling with make use of a little ball shaped cutter.
Ever-power has capability 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 gear CAD versions 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 production of the Globoid gear is more technical compare to manufacturing of the Globoid pinion. The Globoid pinion can be produced in high amounts by turning, whirling or grinding. Through the machining process of the Globoid pinion the slicing tool has to be able to tilt in order to produce the enveloping form.
The newer production methods are under advancement. The most promising creation method of the Globoid pinion can be continues grinding procedure, which includes a grinding steering wheel (diamond or CBN plated) with specific 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 need 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 has developed a computer based tool for generating of 3-dimensional CAD models of grinding equipment for high volume production of the Globoid items.
The most common utilization 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 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 creating the cutting hubs have been developed. As the modern motor vehicle steering systems began to use traditional Bishop or advanced Ever-power adjustable ratio rack and pinion technology, the demand for the Globoid gears offers 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 classic gear theory
Capacity to produce the vr-rack with not involute form for reduced noise
Capability to generate vr-rack with increased ratio gain is:
Cost of vr-rack style is:
Ever-power advanced Variable Ratio rack and pinion high ratio gain technology for electric motor sport racing applications.
Ever-power low noise Variable Ratio rack and pinion not involute technology.
Ever-power pioneered in developing of globoid worm another era of Globoid gears. In 1999 Ever-power released a skew axis Globoid gear as a higher load capacity and increased driving effectiveness option to the classic Globoid equipment.
Ever-power skew axis (wormoid) gear.
It needs to be noted that the name WORMOID does not relate to any scientific term in fact it is something of Dr. Stepan V. Lunin, who was simply the 1st in proposing this design 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 ability of the concept such as conjugated transmission actions and significant boost of number of teeth in the contact compare to the traditional Globoid gear.
CAD 3-d model of Ever-power wormoid gear.
Ever-power happens to be offering assistance for design and development of items based on Ever-power wormoid technology.
It needs to be noted that wormoid equipment style from Ever-power is obviously promising unique advantages review to the basic Globoid (double enveloping) gear. Among the obvious advantages is elevated load capacity because of increased number of one’s teeth in the mesh. The gear torque is usually carried by even more teeth therefore the load on each individual tooth is decreased. The other obvious advantage is boost driving efficiency. As one can see, the part of the pinion with bigger diameter is traveling the corresponding part of the gear, which has a larger diameter aswell. Such of exclusive feature of Ever-power wormoid is missing in the traditional Globoid gear and results in higher sliding velocities and higher friction drug on the classic 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 support mechanisms that are commonly applied to modern automobiles. Due to the higher driving efficiency, wormoid gear set can be designed with increase ration and offer the same driving performance as the initial worm or dual enveloping worm equipment. For instance NSK worm gear steering actuator with a ration around 20:1 delivers about 80% of generating efficiency. The plastic gear would hold about 80 Hm of torque. An alternative solution wormoid gear style from Ever-power will be capable to raise the ratio up to 30:1 and the torque on the gear up to 150 Hm without enhance of the center distance between the gear and the pinion.
ypical Globoid gear.