Cycloidal gearbox

Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, an individual or substance cycloidal cam, cam followers or rollers, and a slow-speed output shaft. The insight shaft attaches to an eccentric drive member that induces eccentric rotation of the cycloidal cam. In compound reducers, the first an eye on the cycloidal cam lobes engages cam supporters in the housing. Cylindrical cam followers become teeth on the internal gear, and the number of cam followers exceeds the number of cam lobes. The second track of substance cam lobes engages with cam followers on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus increasing torque and reducing rate.

Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in regular planetary gearboxes. The gearbox’s compound reduction and can be calculated using:

where nhsg = the number of followers or rollers in the fixed housing and nops = the quantity for followers or rollers in the gradual quickness output shaft (flange).

There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat therapy, and finishing processes, cycloidal variations share fundamental design principles but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made up of three simple force-transmitting elements: a sun gear, three or even more satellite or world gears, and an interior ring gear. In a typical gearbox, the sun gear attaches to the input shaft, which is connected to the servomotor. Sunlight gear transmits electric motor rotation to the satellites which, in turn, rotate in the stationary ring equipment. The ring gear is part of the gearbox casing. Satellite gears rotate on rigid shafts linked to the earth carrier and cause the earth carrier to rotate and, thus, turn the output shaft. The gearbox gives the result shaft higher torque and lower rpm.

Planetary gearboxes generally have solitary or two-equipment stages for reduction ratios which range from 3:1 to 100:1. A third stage could be added for even higher ratios, nonetheless it is not common.

The ratio of a planetary gearbox is calculated using the next formula:where nring = the amount of teeth in the internal ring gear and nsun = the number of teeth in the pinion (input) gear.
Comparing the two
When deciding between cycloidal and planetary gearboxes, engineers should initial consider the precision needed in the application. If backlash and positioning accuracy are crucial, then cycloidal gearboxes offer the most suitable choice. Removing backlash may also help the servomotor manage high-cycle, high-frequency moves.

Next, consider the ratio. Engineers can do this by optimizing the reflected load/gearbox inertia and swiftness for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best torque density, weight, and precision. In fact, few cycloidal reducers provide ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers can be used. Nevertheless, if the required ratio goes beyond 100:1, cycloidal gearboxes keep Cycloidal gearbox advantages because stacking stages is unnecessary, so the gearbox can be shorter and less expensive.
Finally, consider size. The majority of manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes develop in length from one to two and three-stage styles as needed gear ratios go from less than 10:1 to between 11:1 and 100:1, and then to greater than 100:1, respectively.

Conversely, cycloidal reducers are bigger in diameter for the same torque yet are not for as long. The compound reduction cycloidal gear train handles all ratios within the same package size, so higher-ratio cycloidal equipment boxes become even shorter than planetary versions with the same ratios.

Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But selecting the most appropriate gearbox also involves bearing capability, torsional stiffness, shock loads, environmental conditions, duty routine, and life.

From a mechanical perspective, gearboxes have become somewhat of accessories to servomotors. For gearboxes to perform properly and offer engineers with a balance of performance, existence, and value, sizing and selection ought to be determined from the strain side back to the motor instead of the motor out.

Both cycloidal and planetary reducers are appropriate in any industry that uses servos or stepper motors. And although both are epicyclical reducers, the differences between the majority of planetary gearboxes stem more from gear geometry and manufacturing processes instead of principles of operation. But cycloidal reducers are more different and share little in common with each other. There are advantages in each and engineers should consider the strengths and weaknesses when selecting one over the additional.

Benefits of planetary gearboxes
• High torque density
• Load distribution and sharing between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost

Great things about cycloidal gearboxes
• Zero or very-low backlash remains relatively constant during life of the application
• Rolling instead of sliding contact
• Low wear
• Shock-load capacity
• Torsional stiffness
• Flat, pancake design
• Ratios exceeding 200:1 in a concise size
• Quiet operation
The necessity for gearboxes
There are three basic reasons to employ a gearbox:

Inertia matching. The most common reason for selecting a gearbox is to control inertia in highly dynamic situations. Servomotors can only just control up to 10 times their own inertia. But if response time is critical, the engine should control less than four times its own inertia.

Speed reduction, Servomotors run more efficiently at higher speeds. Gearboxes help keep motors operating at their ideal speeds.

Torque magnification. Gearboxes provide mechanical advantage by not merely decreasing swiftness but also increasing output torque.

The EP 3000 and our related products that utilize cycloidal gearing technology deliver the most robust solution in the most compact footprint. The main power train is comprised of an eccentric roller bearing that drives a wheel around a set of internal pins, keeping the decrease high and the rotational inertia low. The wheel incorporates a curved tooth profile instead of the more traditional involute tooth profile, which removes shear forces at any point of contact. This style introduces compression forces, rather than those shear forces that could exist with an involute equipment mesh. That provides numerous functionality benefits such as high shock load capability (>500% of rating), minimal friction and wear, lower mechanical service factors, among many others. The cycloidal design also has a sizable output shaft bearing period, which gives exceptional overhung load features without requiring any extra expensive components.

Cycloidal advantages over various other styles of gearing;

Capable of handling larger “shock” loads (>500%) of rating compared to worm, helical, etc.
High reduction ratios and torque density in a concise dimensional footprint
Exceptional “built-in” overhung load carrying capability
High efficiency (>95%) per reduction stage
Minimal reflected inertia to electric motor for longer service life
Just ridiculously rugged since all get-out
The overall EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP may be the most reliable reducer in the commercial marketplace, in fact it is a perfect fit for applications in heavy industry such as for example oil & gas, major and secondary metal processing, commercial food production, metal trimming and forming machinery, wastewater treatment, extrusion tools, among others.

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