Transfer High Torques Dynamically and with Angular Accuracy

January 11, 2019 - "Press Releases"

Position precisely using helical cut planetary gears
Electric servomotors drive robots, handling systems, carriages and rotary tables on machine tools and inspection and testing machines, as well as components for medical technology equipment. Planetary gearboxes are used advantageously to reduce speed and transfer high torques. The recently introduced G-series gearbox lines from Framo Morat feature minimal circumferential backlash. They are energy efficient, quiet and low-maintenance.
Machine manufacturers prefer driving and positioning various components of their
machines with decentralized, highly dynamic servomotors. For instance, suitable gears are required in order to achieve low rotational speeds and positioning speeds. These gears must be able to significantly reduce high engine speeds (in synchronous motors, up to 8000 rpm) while being able to transfer high torques. The latter is particularly important due to the high dynamics of servomotors. For example, machine carriages on machine tools and handling systems should be able to accelerate quickly in order to achieve the highest travel speeds on the shortest travel lengths within the shortest amount of time.   
Energy efficient, compact, quiet and leak-proof
Furthermore, machine manufacturers and gearoperators require a range of additional features. These should achieve a high degree of efficiency and therefore operate in an extremely energy efficient manner to minimize both energy consumption and overall servomotor design size. Moreover, the gears should be compactly constructed so that they require little installation space, enabling complete servodrive integration into machine enclosures. With special applications, for example when driving medical technology devices or devices in the food industry, operators require particularly smooth, low-vibration and quiet gear operation. In addition, the drive elements must not contaminate the surrounding environment. The gears must therefore be leak proof to prevent the discharge of any oil, lubricant or potential debris. 
Rigid bearings and precision ground helical gearing
The G-series of planetary gearboxes from Framo Morat in Eisenbach meets these extensive demands. With these premium-quality gears, servodrives can be positioned with angular accuracies of less than 3 arcmin, optionally down to even 1 arcmin. Among other things, this makes it possible to precisely position the laser heads on laser cutting machines over large travel distances extending several meters. For this purpose, the gear wheels of the planetary gears are machined and measured within very narrow production tolerances. Then they are paired individually according to precise dimensions and incorporated into the gears. The planetary and sun gears are helically toothed. Their tooth flanks are precision ground. In addition to a minimized circumferential backlash, this ensures quiet operation. This contributes to the high degree of efficiency of planetary gears, therefore operating with energy efficiency. In addition, the precision ground tooth flanks substantially increase the planetary gears' service life and period of application. 

One-piece planetary carriers made from solid metal ensure high torsional rigidity and consequently, highly precise tooth meshing of the gear tooth pairings. The axles of the planetary gears also have fully acicular bearings. This contributes to the ability of the planetary gears to transfer higher than normal torques. Sun pinions mounted with an additional axle bearing provide for a smooth, low-vibration operation of the planetary gears. Prestressed, rigid grooved ball bearings guide the input and output shafts securely and reliably. Accurately aligned seals ensure protection in accordance with IP65. They reliably prevent the grease on the planetary gears, which are lifetime-lubricated, from escaping. They also keep the gear wheels and roller bearings safe from dust, dirt and fluids. 


Five variants for individual requirements

There are five versions available so that machine and device manufacturers with various requirements regarding installation space, circumferential backlash, rotational speed reduction, torques, and radial and axial rigidity can benefit from the advantages of high-quality planetary gears of the G-Series.

The especially compact, short GSD design offers a shaft flange on the output side and is ideally suited for robot application. With its stable, quadratic and single-piece flange housing, the GSB variant is universally usable. It can withstand high axial and radial loads and features exceptional torsional rigidity. Optionally available are both the GSD and the GSB versions, with a circumferential backlash reduced to 1 arcmin. One and two-stage designs feature gear ratios from i=3 to i=100.

For small installation spaces, for example for use on NC rotary and swiveling tables on tool machines, the GSBL variant is made from a combination of bevel and planetary gears as angular gears. Single and double-stage designs implement transmission ratios from i=3 to i=200. 

Requirements for economical yet torsionally rigid and stable gears with gear ratios from i=3 to i=100 can be met with the GSE and GFE designs from Framo Morat. They reach a service life of over 30,000 hours, are lifetime-lubricated and protected in accordance with IP65. The GSN version provides particularly quiet operation thanks to ground helical gearing and higher power density. It offers one-stage and two-stage gears with a housing diameter from 60 to 115 mm. The GFE design features one-stage and two-stage planetary gears with a housing diameter from 50 and 220 mm. The latter can transfer more than 1,500 Nm of nominal drive torque. These gears are particularly suitable for applications in the food industry, such as for driving stirrers, and in the field of medical technology, for instance as a positioning drive for vertically adjustable operation and examination tables.


Picture 1: 
The low-backlash GSB planetary gearbox line is ideally suited for carriage drives in tool machines, such as for laser cutting machines
Picture 2: 
When restrictive requirements are placed on installation space, for example
in rotary and swiveling table drives, the GSBL line of combined planetary and 
bevel gearboxes, designed as angular gearboxes, provide a compelling
Picture 3: 
Compact and highly precise: With their minimal circumferential backlash, the GSD series planetary gears are favored for applications requiring an ideal combination of maximum dynamics and precise positioning. 
Picture 4: 
When moving and positioning heavy loads precisely and quietly, such as when adjusting examination and operating tables, users favor Framo Morat's GFE line of durable, stable and low-backlash planetary gearboxes. 
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