Cycloidal gearbox

Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four fundamental components: a high-speed input shaft, an individual 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 compound reducers, the first an eye on the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers act as teeth on the internal gear, and the amount of cam fans exceeds the amount of cam lobes. The second 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 output shaft, thus raising torque and reducing velocity.

Compound cycloidal gearboxes offer ratios ranging from only 10:1 to 300:1 without stacking levels, as in standard planetary gearboxes. The gearbox’s compound decrease 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 several 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 up 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 motor rotation to the satellites which, subsequently, rotate inside the stationary ring equipment. The ring equipment is section of the gearbox housing. Satellite gears rotate on rigid shafts linked to the earth carrier and trigger 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 Cycloidal gearbox two-equipment stages for reduction ratios which range from 3:1 to 100:1. A third stage could be added for also higher ratios, but it is not common.

The ratio of a planetary gearbox is calculated using the following 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 form. If backlash and positioning precision are necessary, then cycloidal gearboxes offer the best choice. Removing backlash can also help the servomotor deal with high-cycle, high-frequency moves.

Following, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and speed for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide greatest torque density, weight, and precision. Actually, few cycloidal reducers offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers may be used. However, if the required ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking stages is unnecessary, so the gearbox could be shorter and less expensive.
Finally, consider size. Many manufacturers offer square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes grow 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 reduction cycloidal gear train handles all ratios within the same package deal size, therefore higher-ratio cycloidal gear boxes become even shorter than planetary versions with the same ratios.

Backlash, ratio, and size provide engineers with an initial gearbox selection. But deciding on the best gearbox also involves bearing capacity, torsional stiffness, shock loads, environmental conditions, duty routine, and life.

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

Both cycloidal and planetary reducers work in virtually any industry that uses servos or stepper motors. And although both are epicyclical reducers, the distinctions between many planetary gearboxes stem more from gear geometry and manufacturing procedures instead of principles of procedure. But cycloidal reducers are more diverse and share small in common with each other. There are advantages in each and engineers should consider the strengths and weaknesses when choosing one over the various other.

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

Great things about cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during life 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 employ a gearbox:

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

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

Torque magnification. Gearboxes provide mechanical advantage by not only decreasing rate but also increasing result torque.

The EP 3000 and our related products that make use of cycloidal gearing technology deliver the most robust solution in the most compact footprint. The primary power train is comprised of an eccentric roller bearing that drives a wheel around a set of inner pins, keeping the reduction high and the rotational inertia low. The wheel includes a curved tooth profile instead of the more traditional involute tooth profile, which eliminates shear forces at any point of contact. This design introduces compression forces, rather than those shear forces that could can be found with an involute gear mesh. That provides a number of performance benefits such as high shock load capacity (>500% of ranking), minimal friction and use, lower mechanical service elements, among numerous others. The cycloidal design also has a sizable output shaft bearing span, which provides exceptional overhung load capabilities without requiring any additional expensive components.

Cycloidal advantages over additional 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 compact dimensional footprint
Exceptional “built-in” overhung load carrying capability
High efficiency (>95%) per reduction stage
Minimal reflected inertia to motor for longer service life
Just ridiculously rugged as all get-out
The overall EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP is the most dependable reducer in the commercial marketplace, and it is a perfect fit for applications in large industry such as for example oil & gas, primary and secondary metal processing, commercial food production, metal cutting and forming machinery, wastewater treatment, extrusion devices, among others.

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