Cycloidal gearboxes or reducers contain four simple 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 substance reducers, the first an eye on the cycloidal cam lobes engages cam followers in the casing. Cylindrical cam followers act as teeth on the inner gear, and the amount of cam fans exceeds the amount of cam lobes. The next 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 output shaft, thus increasing torque and reducing quickness.
Compound cycloidal gearboxes offer Cycloidal gearbox ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in regular planetary gearboxes. The gearbox’s compound decrease 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 slow swiftness output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat therapy, and finishing processes, cycloidal variations share fundamental design concepts but generate cycloidal movement in different ways.
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or more satellite or planet gears, and an interior ring gear. In a typical gearbox, the sun equipment attaches to the insight shaft, which is connected to the servomotor. Sunlight gear transmits 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 linked to the planet carrier and trigger the planet carrier to rotate and, thus, turn the result shaft. The gearbox provides output shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary or two-equipment stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for even 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 inner 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 first consider the precision needed in the application. If backlash and positioning accuracy are necessary, then cycloidal gearboxes provide most suitable choice. Removing backlash may also help the servomotor deal with high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do this 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. 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. Nevertheless, if the required ratio goes beyond 100:1, cycloidal gearboxes hold advantages because stacking phases is unnecessary, so the gearbox could be shorter and less costly.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes grow in length from one to two and three-stage styles as needed equipment ratios go from 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 but are not for as long. The compound reduction cycloidal gear teach handles all ratios within the same bundle 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 choosing the right gearbox also consists of bearing capacity, 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 provide engineers with a balance of performance, lifestyle, and worth, sizing and selection should be determined from the load side back to the motor instead of 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 distinctions between most planetary gearboxes stem more from gear geometry and manufacturing procedures rather than principles of procedure. But cycloidal reducers are more different 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 remains 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 use a gearbox:
Inertia matching. The most typical reason for selecting a gearbox is to control inertia in highly dynamic circumstances. Servomotors can only control up to 10 times their very own inertia. But if response period is critical, the motor should control less than four situations its own inertia.
Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help to keep motors operating at their ideal speeds.
Torque magnification. Gearboxes offer mechanical advantage by not only decreasing acceleration 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 primary power train is comprised of an eccentric roller bearing that drives a wheel around a couple of inner 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 eliminates shear forces at any point of contact. This design introduces compression forces, rather than those shear forces that would can be found with an involute gear mesh. That provides a number of overall performance benefits such as high shock load capability (>500% of rating), minimal friction and use, lower mechanical service factors, among numerous others. The cycloidal design also has a big output shaft bearing period, which gives exceptional overhung load features without requiring any additional expensive components.
Cycloidal advantages over 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 compact 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 entire EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP is the most reliable reducer in the industrial marketplace, and it is a perfect fit for applications in heavy industry such as for example oil & gas, primary and secondary metal processing, industrial food production, metal trimming and forming machinery, wastewater treatment, extrusion equipment, among others.