Mayr power transmission recently set out to create a compact safety brake in a small construction space with high forces… and all this without using hydraulics. The result was a new, high-performance, pneumatically-released version of the ROBA-guidestop profiled rail brake.
This extended ROBA-guidestop series has a pneumatically-released version which provides new possibilities with its high holding forces. For machines in which a hydraulic system is already available, users can still use the hydraulically-released ROBA-guidestop safety brakes. However, in applications where a hydraulics system would have to be installed first to operate a brake with high holding forces, the pneumatically-released ROBA-guidestop safety brake is now used. It clamps profiled rails accurately and backlash-free with the same holding forces as the hydraulic design of the brake.
The pneumatic ROBA-guidestop is opened with compressed air at 20 to 30 bar. To achieve the proper operating pressure, operators use a compact pressure booster in combination with the brake, mechanically increasing the system pressure from 4 to 6 bar as is usual in pneumatic networks, without the use of external energy. This concept enables a selective pressure increase directly prior to the brake, i.e. directly in the system where the higher pressure is required — as a result, short high-pressure lines suffice. The pneumatic ROBA-guidestop safety brake is available in five construction sizes — each size in both a standard design and in a compact, short design — covering a range of holding forces from 1 to 34 kN. The brake is designed for the different rail construction sizes of conventional linear guidance manufacturers.
Safety
Image: mayr power transmission.
Just like the hydraulic brake design, the pneumatic ROBA-guidestop safety brake acts with high rigidity directly applied to the linear guidance. This means that the safety brake is mounted directly on the masses that should be held. This configuration reduces hazards, especially concerning gravity-loaded axes. Drive elements between the motor and the moving mass, such as spindles, spindle nuts, shaft couplings or gearboxes, have no influence on safety — as opposed to the concepts using motor brakes, where all drive elements transmit the braking torque to the carriage. Systems using ROB-guidestop safety brakes therefore enable a significantly higher rigidity than solutions featuring rotary brakes integrated into servomotors.
Backlash-free clamping advantages: The additional rigidity of the NC axis increases process accuracy, improves machining performance and can provide further technological advantages for heavy machining. The machining produces less vibration, improving workpiece surface quality. In case of a stationary axis during machining, the brake can absorb the load. As a result, the drive motor can be switched off and removed from the controls. This eliminates control movements and is gentle on the ball screw spindle. The closed brake absorbs the axial forces. The service life and maintenance intervals of the drive components are extended.
The brakes of the ROBA-guidestop series operate according to a fail-safe principle, i.e. they are closed in a de-energized condition. They reliably guarantee operational and functional safety in machines and systems around the globe.
Mayr
www.mayr.com/en
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