Cycloidal gearboxes or reducers consist of four simple components: a high-speed input shaft, an individual or substance 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 substance reducers, the first an eye on the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers become teeth on the internal gear, and the number of cam fans exceeds the amount of cam lobes. The next track of substance 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 provide ratios ranging from only 10:1 to 300:1 without stacking stages, as in regular planetary gearboxes. The gearbox’s compound decrease and will 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 gradual velocity output shaft (flange).
There are several 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 movement in different ways.
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or more satellite or world gears, and an interior ring gear. In an average gearbox, the sun gear attaches to the insight shaft, which is connected to the servomotor. Sunlight gear transmits motor rotation to the satellites which, in turn, rotate inside the stationary ring gear. The ring equipment is portion of the gearbox housing. Satellite gears rotate on rigid shafts connected to the planet 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 one or two-gear stages for reduction ratios which range from 3:1 to 100:1. A third stage can 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 amount of teeth in the pinion (input) gear.
Comparing the two
When deciding among cycloidal and planetary gearboxes, engineers should initial consider the precision needed in the application. If backlash and positioning precision are necessary, then cycloidal gearboxes offer the most suitable choice. Removing backlash may also help the servomotor deal with high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and rate 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 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 levels is unnecessary, therefore the gearbox could be shorter and less expensive.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate precisely with servomotors. But planetary gearboxes grow in length from single 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 higher 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 bundle size, so 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 cycle, 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, life, and worth, 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 any industry that uses servos or stepper motors. And although both are epicyclical reducers, the distinctions between many 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 consider the strengths and weaknesses when choosing one over the 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 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 need 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 powerful 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 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 swiftness but also increasing output 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 made up 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 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 style introduces compression forces, rather than those shear forces that could exist with an involute equipment mesh. That provides several functionality benefits such as for example high shock load capacity (>500% of rating), minimal friction and put on, lower mechanical service factors, among numerous others. The cycloidal design also has a large output shaft bearing span, which gives exceptional Cycloidal gearbox 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 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 as all get-out
The entire EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP is the most dependable reducer in the commercial marketplace, and it is a perfect match for applications in weighty industry such as for example oil & gas, main and secondary metal processing, industrial food production, metal cutting and forming machinery, wastewater treatment, extrusion tools, among others.