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 (on the subject of 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 merely with the mating enveloping equipment but also with a properly designed cylindrical helical gear. Using a helical equipment with a Globoid pinion is normally common in lower cost in applications such as automotive electric powered gear actuators. The significant cost advantage comes because of the probability 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. Nevertheless 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, positioned in Traverse City, MI. The detailed details about procedures used at Cone Drive for making 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 little ball shaped cutter.
Ever-power has capacity to design, prototype and offer Globoid gear products. 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 gear 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 needs to be noted that manufacturing 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 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 globoid worm creation method of the Globoid pinion is normally continues grinding procedure, which incorporates 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 have to generate a correct kind of the Globoid pinion without tilting therefore the production rate and the production price would be significantly reduced. Ever-power has developed a computer based device for generating of 3-dimensional CAD types of grinding tools for high volume creation 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 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. As the modern motor vehicle steering systems started to use classic 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
Capability to generate vr-rack with an increase of ratio gain is:
Cost of vr-rack style is:
Ever-power advanced Variable Ratio rack and pinion high ratio gain technology for engine 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 gear.
Ever-power skew axis (wormoid) gear.
It needs to be noted that the name WORMOID will not relate with any scientific term and it is something of Dr. Stepan V. Lunin, who was the initial in proposing this design and, moreover, he was the first who produces an accurate operating model of the apparatus 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 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 style from Ever-power is actually promising unique advantages compare to the classic Globoid (double enveloping) equipment. Among the obvious advantages is improved load capacity because of increased number of the teeth in the mesh. The apparatus torque is usually carried by more teeth therefore the load on every individual tooth is reduced. The other obvious advantage is boost driving efficiency. As one can see, the part of the pinion with larger diameter is generating the corresponding portion of the gear, which has a larger diameter aswell. Such of exclusive feature of Ever-power wormoid is definitely missing in the traditional Globoid gear and outcomes in higher sliding velocities and higher friction drug on the traditional globoid gear. A skilled in the artwork engineer would instantly derive possible design advantages of the wormoid gear. For instance, using of the wormoid gear can significantly reduce cost of electric powered support mechanisms that are commonly applied to modern automobiles. Because of the bigger driving efficiency, wormoid equipment set can be made with increase ration and offer the same driving effectiveness as the initial worm or dual enveloping worm gear. For instance NSK worm gear steering actuator with a ration of about 20:1 delivers about 80% of driving 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 gear and the pinion.
ypical Globoid gear.