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 can mesh not only with the mating enveloping gear but also with a correctly designed cylindrical helical equipment. Using a helical gear with a Globoid pinion is usually common in lower cost in applications such as automotive electric powered gear actuators. The significant cost advantage comes due to the probability to injection mold the helical plastic gear. The load capability of the simplified helical/Globoid transmission is decreased to the particular level below the load capacity of the regular worm gear. Nevertheless the driving efficiency is still better compare to the standard worm gear.
There are only a few suppliers of the Globoid gear. division of Textron, located in Traverse City, MI. The detailed information regarding procedures used at Cone Drive for developing of its gear cannot be found. However, based on publicly released details it can be understood that the apparatus is manufactured by CNC milling with make use of a small ball shaped cutter.
Ever-power has capability 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 versions can be used in various CNC machining shops for creating globoid gear at globoid worm considerably reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It has to be noted that production of the Globoid equipment is more technical compare to production of the Globoid pinion. The Globoid pinion can be produced in high quantities by turning, whirling or grinding. Through the machining procedure for the Globoid pinion the slicing tool needs to be capable to tilt in order to produce the enveloping form.
The newer production methods are under advancement. The most promising production method of the Globoid pinion is definitely continues grinding procedure, which incorporates 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 device. The grinding tooth would have to generate a correct type of the Globoid pinion without tilting so the production price and the production cost would be considerably reduced. Ever-power is rolling out a computer based device for generating of 3-dimensional CAD types of grinding equipment for high volume production of the Globoid items.
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 been cut by a particular hub, which replicated the form of the Globoid Pinion. Special machines for producing the reducing hubs have been developed. As the modern automotive 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 based on:
Rack geometry calculation precision 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 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 generation of Globoid gears. In 1999 Ever-power released a skew axis Globoid gear as a high load capability and increased driving efficiency option to the classic Globoid equipment.
Ever-power skew axis (wormoid) gear.
It has 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 initial in proposing this style and, moreover, he was the 1st who produces a precise working 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 increase 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 design and development of items predicated on Ever-power wormoid technology.
It needs to be noted that wormoid gear style from Ever-power is actually promising unique advantages review to the vintage Globoid (double enveloping) equipment. One of the obvious advantages is improved load capacity because of increased number of the teeth in the mesh. The apparatus torque can be carried by even more teeth so the load on every individual tooth is decreased. The other apparent advantage is increase driving efficiency. As you can see, the portion 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 is normally missing in the classic Globoid gear and results in higher sliding velocities and higher friction medication on the traditional globoid gear. A skilled in the art engineer would instantly derive possible design benefits of the wormoid gear. For instance, using of the wormoid equipment can significantly reduce cost of electric powered support mechanisms that are commonly used on modern automobiles. Because of the higher 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 example NSK worm gear steering actuator with a ration around 20:1 delivers about 80% of generating efficiency. The plastic equipment would hold about 80 Hm of torque. An alternative wormoid gear style from Ever-power would be capable to boost the ratio up to 30:1 and the torque on the apparatus up to 150 Hm without increase of the center distance between the equipment and the pinion.
ypical Globoid gear.