Cycloidal gearboxes or reducers consist of 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 track of the cycloidal cam lobes engages cam followers in the casing. Cylindrical cam followers act as teeth on the internal gear, and the number of cam fans exceeds the number of cam lobes. The second track of substance cam lobes engages with cam supporters on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing velocity.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking levels, as in standard planetary gearboxes. The gearbox’s compound decrease and can be calculated using:
where nhsg = the number of followers or rollers in the fixed housing and nops = the number for followers or rollers in the slower velocity output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat therapy, and finishing procedures, cycloidal variations share fundamental design concepts but generate cycloidal motion in different ways.
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or even more satellite or world gears, and an internal ring gear. In a typical gearbox, the sun equipment attaches to the insight shaft, which is connected to the servomotor. The sun gear transmits electric motor rotation to the satellites which, subsequently, rotate in the stationary ring gear. The ring gear is section of the gearbox housing. Satellite gears rotate on rigid shafts connected to the planet carrier and cause the planet carrier to rotate and, thus, turn the result shaft. The gearbox gives the output shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary 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 number 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. If backlash and positioning precision are necessary, then cycloidal gearboxes offer the best choice. Removing backlash can also help the servomotor handle 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 provide 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. However, if the required ratio goes beyond 100:1, cycloidal gearboxes hold advantages because stacking phases is unnecessary, therefore the gearbox could be shorter and less costly.
Finally, consider size. Many manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes grow in length from solitary 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 teach handles all ratios within the same package size, so higher-ratio cycloidal gear boxes become also 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 requires bearing capacity, torsional stiffness, shock loads, environmental conditions, duty cycle, and life.
From a mechanical perspective, gearboxes have become somewhat of accessories to servomotors. For gearboxes to execute properly and offer engineers with a balance of performance, existence, and worth, sizing and selection ought to be determined from the strain side back again to the motor instead of the motor out.
Both cycloidal and planetary reducers are appropriate in virtually any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the variations between many planetary gearboxes stem more from equipment geometry and Cycloidal gearbox manufacturing procedures instead of principles of operation. But cycloidal reducers are more different and share small in common with each other. There are advantages in each and engineers should consider the strengths and weaknesses when choosing 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
Benefits of cycloidal gearboxes
• Zero or very-low backlash remains 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 concise size
• Quiet operation
The necessity 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 circumstances. Servomotors can only control up to 10 times their own inertia. But if response time is critical, the engine should control less than four moments its own inertia.
Speed reduction, Servomotors run more efficiently at higher speeds. Gearboxes help keep motors working at their ideal 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 use 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 inner pins, keeping the decrease high and the rotational inertia low. The wheel includes a curved tooth profile instead of the more traditional involute tooth profile, which gets rid of shear forces at any stage of contact. This style introduces compression forces, instead of those shear forces that could can be found with an involute equipment mesh. That provides several functionality benefits such as for example high shock load capacity (>500% of ranking), minimal friction and put on, lower mechanical service factors, among numerous others. The cycloidal style also has a large output shaft bearing period, which gives exceptional overhung load capabilities without requiring any additional expensive components.
Cycloidal advantages over various other 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 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 because all get-out
The overall 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 large industry such as for example oil & gas, principal and secondary steel processing, industrial food production, metal slicing and forming machinery, wastewater treatment, extrusion equipment, among others.