Cycloidal gearbox

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

Compound cycloidal gearboxes offer Cycloidal gearbox Ratios ranging from only 10:1 to 300:1 without stacking levels, as in standard planetary gearboxes. The gearbox’s compound reduction and can be calculated using:

where nhsg = the amount of followers or rollers in the fixed housing and nops = the quantity for followers or rollers in the slower acceleration output shaft (flange).

There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat treatment, and finishing processes, cycloidal variations share basic design concepts but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made of three fundamental force-transmitting elements: a sun gear, three or even more satellite or world gears, and an internal ring gear. In an average gearbox, the sun gear attaches to the insight shaft, which is linked to the servomotor. Sunlight gear transmits electric motor rotation to the satellites which, subsequently, rotate within the stationary ring equipment. The ring gear is area of the gearbox casing. Satellite gears rotate on rigid shafts connected to the planet carrier and trigger the planet carrier to rotate and, thus, turn the output shaft. The gearbox provides output shaft higher torque and lower rpm.

Planetary gearboxes generally have one or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for also 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 inner ring gear and nsun = the number of teeth in the pinion (input) gear.
Comparing the two
When deciding among cycloidal and planetary gearboxes, engineers should first consider the precision needed in the application. If backlash and positioning accuracy are crucial, then cycloidal gearboxes provide most suitable choice. Removing backlash can also help the servomotor handle high-cycle, high-frequency moves.

Next, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and acceleration for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes offer the best torque density, weight, and precision. Actually, not many cycloidal reducers offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers can be used. However, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking levels is unnecessary, therefore the gearbox can be shorter and less costly.
Finally, consider size. The majority of manufacturers provide square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes develop in length from solitary to two and three-stage styles as needed equipment ratios go from less than 10:1 to between 11:1 and 100:1, and to greater than 100:1, respectively.

Conversely, cycloidal reducers are bigger in diameter for the same torque but are not as long. The compound decrease cycloidal gear teach handles all ratios within the same bundle size, therefore higher-ratio cycloidal equipment boxes become even shorter than planetary versions with the same ratios.

Backlash, ratio, and size provide engineers with an initial gearbox selection. But choosing the right gearbox also consists of bearing capability, torsional stiffness, shock loads, environmental conditions, duty cycle, and life.

From a mechanical perspective, gearboxes have become somewhat of accessories to servomotors. For gearboxes to perform properly and provide engineers with a stability of performance, lifestyle, and worth, sizing and selection ought to be determined from the load side back again to the motor as opposed to the motor out.

Both cycloidal and planetary reducers work in any industry that uses servos or stepper motors. And although both are epicyclical reducers, the variations between most planetary gearboxes stem more from equipment geometry and manufacturing processes rather than principles of procedure. But cycloidal reducers are more different and share little in common with one another. There are advantages in each and engineers should consider the strengths and weaknesses when selecting one over the various other.

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

Benefits of cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during existence of the application
• Rolling rather than 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 use a gearbox:

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

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

Torque magnification. Gearboxes offer mechanical advantage by not merely decreasing speed but also increasing output torque.

The EP 3000 and our related products that use 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 couple of internal pins, keeping the reduction high and the rotational inertia low. The wheel incorporates a curved tooth profile rather than the more traditional involute tooth profile, which gets rid of shear forces at any point of contact. This style introduces compression forces, rather than those shear forces that would can be found with an involute gear mesh. That provides several performance benefits such as for example high shock load capacity (>500% of rating), minimal friction and wear, lower mechanical service elements, among many others. The cycloidal style also has a big output shaft bearing period, which gives exceptional overhung load features without requiring any extra expensive components.

Cycloidal advantages over other styles of gearing;

Capable of handling larger “shock” loads (>500%) of rating in comparison 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 as all get-out
The overall EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP may be the most dependable reducer in the commercial marketplace, in fact it is a perfect fit for applications in large industry such as oil & gas, main and secondary steel processing, industrial food production, metal trimming and forming machinery, wastewater treatment, extrusion equipment, among others.

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