Cycloidal gearbox

Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four simple components: a high-speed input shaft, a single or substance 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 tabs on the cycloidal cam lobes engages cam fans in the casing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam supporters exceeds the amount of cam lobes. The next track of substance cam lobes engages with cam followers on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing quickness.

Compound cycloidal gearboxes provide ratios ranging from only 10:1 to 300:1 without stacking stages, 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 slow quickness 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 procedures, cycloidal variations share simple 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 interior ring gear. In an average gearbox, the sun equipment attaches to the insight shaft, which is connected to the servomotor. Sunlight gear transmits electric motor rotation to the satellites which, subsequently, rotate inside the stationary ring gear. The ring equipment is portion of the gearbox housing. Satellite gears rotate on rigid shafts linked to the planet carrier and trigger the earth carrier to rotate and, thus, turn the output shaft. The gearbox gives the output 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 can be added for actually higher ratios, nonetheless it is not common.

The ratio of a planetary gearbox is calculated using the following 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 between 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 may also help the servomotor manage 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 offer the best torque density, weight, and precision. In fact, 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 hold advantages because stacking phases is unnecessary, so the gearbox can be shorter and less expensive.
Finally, consider size. The majority of manufacturers offer square-framed planetary gearboxes that mate precisely with servomotors. But planetary gearboxes grow in length from one to two and three-stage designs as needed equipment ratios go from significantly less than 10:1 to between 11:1 and 100:1, and then to higher than 100:1, respectively.

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

Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But selecting the most appropriate gearbox also requires 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 stability of performance, lifestyle, and value, sizing and selection should be determined from the strain side back again to the motor as opposed to the motor out.

Both cycloidal and planetary reducers work in virtually any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the distinctions between the majority of planetary gearboxes stem more from equipment geometry and manufacturing procedures rather than principles of procedure. But cycloidal reducers are more diverse and share little in common with each other. There are advantages in each and engineers should think about the strengths and weaknesses when selecting one over the 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 lifestyle of the application
• Rolling instead of sliding contact
• Low wear
• Shock-load capacity
• Torsional stiffness
• Flat, pancake design
• Ratios exceeding 200:1 in a compact size
• Quiet operation
The necessity for gearboxes
There are three basic reasons to use a gearbox:

Inertia matching. The most common reason for choosing the 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 motor should control less than four instances its own inertia.

Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help to keep motors working at their ideal speeds.

Torque magnification. Gearboxes offer mechanical advantage by not only decreasing swiftness 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 made up of an eccentric roller bearing that drives a wheel around a set of inner pins, keeping the decrease high and the rotational inertia low. The wheel includes a curved tooth profile rather than the more traditional involute tooth profile, which gets rid of 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 Cycloidal gearbox provides numerous overall performance benefits such as for example high shock load capability (>500% of ranking), minimal friction and use, lower mechanical service factors, among many others. The cycloidal design also has a huge output shaft bearing period, which gives exceptional overhung load features without requiring any extra 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 concise dimensional footprint
Exceptional “built-in” overhung load carrying capability
High efficiency (>95%) per reduction stage
Minimal reflected inertia to engine for longer service life
Just ridiculously rugged because all get-out
The entire 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, and it is a perfect fit for applications in heavy industry such as for example oil & gas, main and secondary metal processing, commercial food production, metal trimming and forming machinery, wastewater treatment, extrusion devices, among others.

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