Technical Papers

Be on the safe side with the drive technology by SIEB & MEYER

Safety functions already integrated

All frequency converters and servo amplifiers of series SD2x are equipped with the function load indicator as standard. The function enables to detect load changes of the connected motor. Furthermore, SIEB & MEYER provides users of drive system SD2 with two sensorless safety functions as standard. These were developed especially for rotary motors without speed sensors.

The load indicator integrated in the frequency converters and servo amplifiers of series SD2x is not based on acoustic sensors, but evaluates the actual torque-forming current of the motor. Hence, load changes of the motor are determined very precisely. This, in turn, allows drawing conclusions on tool breakage or tool wear. Additionally, the load indicator can detect the contact between tool and work piece (gap eliminator). Last but not least, feed rates can be flexibly adjusted by means of the load indicator.

However, tool breakage does not pose the only possible danger to processing machines and machine tools. Tools that are still rotating or rotating at too high speeds are also a risk to the operator or the service technician. To avoid such risks SIEB & MEYER has extended the functional spectrum of drive system SD2 with the sensorless functions Safe Frequency Monitor (SFM) and Safe Limited Output Frequency (SLOF). The safety function SFM enables the operator to safely detect whether or not the speed of a sensorless spindle has reached standstill or dropped below a safe speed value after switch-off. The safety function SLOF is used to make sure that critical speeds are not exceeded. Both safety functions are approved by TÜV Nord according to EN 61508:2010 and are based on the function Safe Torque Off (STO) which is also integrated as standard. The result is a functional and low-cost solution for sensorless systems. Hence, it is not necessary to equip already existing or new spindles or motors with sensors.

"Both the safety functions and the integrated load indicator offer a real added value to manufacturers of processing machines and machine tools," Torsten Blankenburg, CTO SIEB & MEYER AG, says. "In addition, the solution fills a gap in the market – in line with the motto of SIEB & MEYER regarding the continuous development of well-proven products based on the customer needs."

 

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