Cycloidal gearbox cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, an individual or compound 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 track of the cycloidal cam lobes engages cam fans in the casing. Cylindrical cam followers act as teeth on the inner gear, and the amount of cam supporters exceeds the amount of cam lobes. The second track of compound cam lobes engages with cam fans on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus raising torque and reducing speed.
Compound cycloidal gearboxes offer ratios ranging from only 10:1 to 300:1 without stacking stages, as in standard planetary gearboxes. The gearbox’s compound reduction and may be calculated using:
where nhsg = the amount of followers or rollers in the fixed housing and nops = the number for followers or rollers in the gradual speed output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat treatment, and finishing processes, cycloidal variations share simple design principles but generate cycloidal motion in different ways.
Planetary gearboxes are made of three fundamental force-transmitting elements: a sun gear, three or more satellite or world gears, and an internal ring gear. In a typical gearbox, the sun equipment attaches to the insight shaft, which is linked to the servomotor. Sunlight gear transmits electric motor rotation to the satellites which, in turn, rotate in the stationary ring gear. The ring equipment is section of the gearbox casing. Satellite gears rotate on rigid shafts connected to the earth carrier and cause the earth carrier to rotate and, thus, turn the result shaft. The gearbox provides result 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 number of teeth in the internal ring gear and nsun = the amount of teeth in the pinion (input) gear.
Comparing the two
When deciding among cycloidal and planetary gearboxes, engineers should 1st consider the precision needed in the application form. 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.
Following, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and velocity for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes offer the greatest torque density, weight, and precision. Actually, not many cycloidal reducers provide ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers may be used. Nevertheless, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes hold advantages because stacking levels 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 specifically with servomotors. But planetary gearboxes develop in length from solitary to two and three-stage styles as needed equipment ratios go from significantly less than 10:1 to between 11:1 and 100:1, and to greater than 100:1, respectively.
Conversely, cycloidal reducers are larger in diameter for the same torque yet are not as long. The compound reduction cycloidal gear teach handles all ratios within the same package size, therefore higher-ratio cycloidal gear boxes become actually shorter than planetary variations with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But deciding on the best gearbox also entails 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 execute properly and provide engineers with a balance of performance, life, and value, sizing and selection ought to be determined from the strain side back to the motor as opposed to the motor out.
Both cycloidal and planetary reducers are appropriate in virtually any industry that uses servos or stepper motors. And although both are epicyclical reducers, the distinctions between most planetary gearboxes stem more from equipment geometry and manufacturing processes rather than principles of procedure. But cycloidal reducers are more diverse and share small in common with one another. There are advantages in each and engineers should think about the strengths and weaknesses when choosing 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
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 concise size
• Quiet operation
The necessity for gearboxes
There are three basic reasons to employ a gearbox:
Inertia matching. The most typical reason for selecting a gearbox is to regulate inertia in highly dynamic situations. Servomotors can only just control up to 10 times their very own inertia. But if response time is critical, the electric motor should control significantly less than four times its own inertia.
Speed reduction, Servomotors run 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 acceleration but also increasing result torque.
The EP 3000 and our related products that use cycloidal gearing technology deliver the most robust solution in the most compact footprint. The primary power train is made up of an eccentric roller bearing that drives a wheel around a couple of internal 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 removes shear forces at any point of contact. This design introduces compression forces, rather than those shear forces that would exist with an involute gear mesh. That provides numerous efficiency benefits such as for example high shock load capacity (>500% of rating), minimal friction and put on, lower mechanical service elements, among numerous others. The cycloidal design also has a huge output shaft bearing period, which provides exceptional overhung load features without requiring any extra expensive components.
Cycloidal advantages over additional styles of gearing;
Able to handle larger “shock” loads (>500%) of rating compared 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 entire EP design proves to be extremely durable, and it needs 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 oil & gas, primary and secondary metal processing, commercial food production, metal slicing and forming machinery, wastewater treatment, extrusion products, among others.