Cycloidal gearboxes or reducers consist of four fundamental components: a high-speed input shaft, a single or substance 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 tabs on the cycloidal cam lobes engages cam supporters in the casing. Cylindrical cam followers become teeth on the internal gear, and the amount of cam fans exceeds the number of cam lobes. The next track of substance cam lobes engages with cam fans on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus increasing torque and reducing swiftness.
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 amount of followers or rollers in the fixed housing and nops = the quantity for followers or rollers in the slower acceleration output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat therapy, and finishing processes, cycloidal variations share simple design principles but generate cycloidal motion in different ways.
Planetary gearboxes are made up of three basic 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 gear attaches to the insight shaft, which is connected to the servomotor. Sunlight gear transmits motor rotation to the satellites which, subsequently, rotate in the stationary ring gear. The ring gear is section of the gearbox casing. Satellite gears rotate on rigid shafts linked to the earth carrier and trigger the earth carrier to rotate and, thus, turn the result shaft. The gearbox gives the result shaft higher torque and lower rpm.
Planetary gearboxes generally have single or two-equipment 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 inner 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 initial consider the precision needed in the application form. If backlash and positioning accuracy are necessary, then cycloidal gearboxes provide most suitable choice. Removing backlash can also help the servomotor deal with high-cycle, high-frequency moves.
Following, 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 provide best torque density, weight, and precision. Actually, few 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, therefore the gearbox could be shorter and less expensive.
Finally, consider size. Many manufacturers offer 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 to greater than 100:1, respectively.
Conversely, cycloidal reducers are larger in diameter for the same torque yet are not for as long. The compound decrease cycloidal gear train handles all ratios within the same package deal size, therefore higher-ratio cycloidal gear boxes become actually shorter than planetary variations with the same ratios.
Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But selecting the most appropriate gearbox also involves 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 stability of performance, existence, and worth, sizing and selection ought to be determined from the load side back to the motor as opposed to the motor out.
Both cycloidal and planetary reducers work in any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the variations 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 little in Cycloidal gearbox common with one another. There are advantages in each and engineers should think about the strengths and weaknesses when selecting 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 compact size
• Quiet operation
The necessity for gearboxes
There are three basic reasons to employ a gearbox:
Inertia matching. The most common reason for choosing the gearbox is to control inertia in highly dynamic situations. Servomotors can only control up to 10 times their very own inertia. But if response time is critical, the engine should control less than four instances its own inertia.
Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help keep motors working at their ideal speeds.
Torque magnification. Gearboxes offer mechanical advantage by not only decreasing quickness 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 main power train is made up 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 exist with an involute equipment mesh. That provides a number of performance benefits such as high shock load capacity (>500% of rating), minimal friction and wear, lower mechanical service elements, among many others. The cycloidal style also has a huge output shaft bearing span, 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 needs minimal maintenance following installation. The EP may be the most reliable reducer in the industrial marketplace, in fact it is a perfect match for applications in large industry such as oil & gas, major and secondary steel processing, industrial food production, metal trimming and forming machinery, wastewater treatment, extrusion devices, among others.