Cycloidal gearboxes or reducers contain four basic 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 compound reducers, the first an eye on the cycloidal cam lobes engages cam followers in the casing. Cylindrical cam followers become 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 result shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing rate.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in standard 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 sluggish acceleration 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 movement in different ways.
Planetary gearboxes are made of three basic force-transmitting elements: a sun gear, three or even more satellite or planet gears, and an internal ring gear. In a typical gearbox, the sun gear attaches to the insight shaft, which is linked to the servomotor. Sunlight gear Cycloidal gearbox transmits engine rotation to the satellites which, subsequently, rotate in the stationary ring gear. The ring gear is part of the gearbox casing. Satellite gears rotate on rigid shafts connected to the earth 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 one or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage can be added for also higher ratios, but it is not common.
The ratio of a planetary gearbox is calculated using the next formula:where nring = the amount 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 first consider the precision needed in the application form. If backlash and positioning accuracy are necessary, then cycloidal gearboxes provide best choice. Removing backlash may also help the servomotor handle high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do this by optimizing the reflected load/gearbox inertia and velocity for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best 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 required ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking phases is unnecessary, therefore the gearbox can be shorter and less costly.
Finally, consider size. The majority of manufacturers provide square-framed planetary gearboxes that mate precisely with servomotors. But planetary gearboxes develop 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 then to greater 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 train handles all ratios within the same deal size, so higher-ratio cycloidal gear boxes become even shorter than planetary versions with the same ratios.
Backlash, ratio, and size provide engineers with a preliminary 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 grown to be somewhat of accessories to servomotors. For gearboxes to perform properly and provide engineers with a stability 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 work in virtually any industry that uses servos or stepper motors. And although both are epicyclical reducers, the variations between many planetary gearboxes stem more from gear geometry and manufacturing procedures rather than 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 selecting 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
Benefits of cycloidal gearboxes
• Zero or very-low backlash remains relatively constant during lifestyle 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 need for gearboxes
There are three basic reasons to employ a gearbox:
Inertia matching. The most typical reason for choosing the 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 engine should control significantly less than four times its own inertia.
Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help keep motors operating at their ideal speeds.
Torque magnification. Gearboxes offer 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 main power train is comprised 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 incorporates a curved tooth profile rather than the more traditional involute tooth profile, which eliminates shear forces at any stage of contact. This style introduces compression forces, rather than those shear forces that would can be found with an involute equipment mesh. That provides numerous efficiency benefits such as for example high shock load capability (>500% of ranking), minimal friction and wear, lower mechanical service factors, among numerous others. The cycloidal style also has a large output shaft bearing period, which provides exceptional overhung load features without requiring any additional expensive components.
Cycloidal advantages over additional styles of gearing;
Able to handle 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 engine for longer service life
Just ridiculously rugged since all get-out
The entire EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP may be the most reliable reducer in the industrial marketplace, and it is a perfect fit for applications in weighty industry such as for example oil & gas, primary and secondary steel processing, industrial food production, metal slicing and forming machinery, wastewater treatment, extrusion gear, among others.