ypical Globoid gear.
Globoid (or Double Enveloping Worm or Hour Glass) gear has advantage pitched against a traditional worm gear 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 manufacturing 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 equipment with a Globoid pinion is common in lower cost in applications such as for example automotive electric powered equipment actuators. The significant cost advantage comes because of the probability to injection mold the helical plastic material gear. The load capacity of the simplified helical/Globoid transmission is reduced to the particular level below the strain capacity of the standard worm gear. However the driving efficiency is still better evaluate to the standard worm gear.
There are only a few suppliers of the Globoid gear. division of Textron, located in Traverse Town, MI. The detailed information regarding processes utilized at Cone Drive for developing of its gear could not be found. However, predicated on publicly released information it can be understood that the gear is manufactured by CNC milling with make use of a little ball shaped cutter.
Ever-power has capacity to design, prototype and supply Globoid gear items. The knowledge 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 generating 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 technical compare to manufacturing of the Globoid pinion. The Globoid pinion could be produced in high quantities by turning, whirling or grinding. During the machining process of the Globoid pinion the reducing tool has to be able to tilt to be able to produce the enveloping shape.
The newer production methods are under advancement. The most promising creation method of the Globoid pinion is certainly 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 difficulties with simulation of the geometry of the grinding tool. The grinding tooth would have to generate a correct kind of the Globoid pinion without globoid worm tilting so the production price and the production cost would be significantly reduced. Ever-power is rolling out a computer based device for producing 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 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 form of the Globoid Pinion. Special machines for creating the cutting hubs have been developed. Because the modern automotive steering systems started to use traditional 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:
Underlying mathematical model is founded on:
Rack geometry calculation accuracy is:
Limited by the boundaries of the classic gear theory
Capability to produce the vr-rack with not involute form for reduced noise
Capability to generate vr-rack with an increase of 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 the next era of Globoid gears. In 1999 Ever-power launched a skew axis Globoid gear as a high load capability 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 to any scientific term in fact it is something of Dr. Stepan V. Lunin, who was the initial in proposing this design and, moreover, he was the first who produces a precise working 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 for example conjugated transmission action and significant boost 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 basic Globoid (double enveloping) equipment. One of the obvious advantages is elevated load capacity because of increased number of the teeth in the mesh. The gear torque is definitely carried by even more teeth so the load on each individual tooth is decreased. The other apparent advantage is increase driving efficiency. As one can see, the part of the pinion with larger diameter is traveling the corresponding portion of the gear, that includes a larger diameter as well. Such of exclusive feature of Ever-power wormoid is normally missing in the traditional Globoid gear and results in higher sliding velocities and higher friction medication on the traditional globoid gear. An experienced in the artwork engineer would instantly derive possible design benefits of the wormoid equipment. For example, using of the wormoid gear can significantly reduce price of electric powered support mechanisms that are commonly applied to modern automobiles. Because of the bigger driving efficiency, wormoid gear set can be made with increase ration and offer the same driving effectiveness as the original worm or double enveloping worm equipment. For instance NSK worm gear steering actuator with a ration around 20:1 delivers about 80% of driving efficiency. The plastic gear 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 gear up to 150 Hm without increase of the guts distance between the gear and the pinion.
ypical Globoid gear.