CNC retrofit raises gear grinder output, accuracy

A Pfauter Kapp gear grinder has been successfully retrofitted with a Siemens Sinumerik 840D CNC to improve productivity by 40% and raise the machine's accuracy.
In early 2005 CNC Design performed a retrofit on a Pfauter Kapp PE1000G gear grinder at David Brown Gear Industries' Woolongong plant. The heat treatment process used to harden gears and pinions distorts them slightly, so before being fitted to a gearbox these workpieces must be ground to eliminate this distortion. The Pfauter Kapp grinding machine, originally built in 1988 performs this critical final step in the production process.

However the hardware and software used on the machine was becoming obsolete and hard to maintain while the user interface was difficult to learn and inflexible.

The retrofit involved the installation of Siemens 1FT6 digital servo motors to all feed axes.

These motors are controlled by Simodrive 611D digital drives which allow the use of feedforward control.

This provides extremely stiff control and fast machine response which is evident in the smooth surface finish on the gear teeth being ground.

The existing spindle motor was retained and connected to a new 611U drive.

The drives are controlled by a Sinumerik 840D CNC.

This is the only product on the market offering integrated safety features.

Sinumerik Safety Integrated is now responsible for monitoring the working space and ensuring the safety of the operator during workpiece set-up and while checking results.

Safe Standstill monitoring, Safe Speeds and Safe External Stops are implemented to create maximum operator safety at all times.

A new user interface was developed in consultation with the machine operators to allow flexible and intuitive control of the grinding process.

The interface runs on a PCU50 control panel which allows grinding and setup data to be saved to the internal hard disk.

Not only did the upgrade provide an easy to understand and intuitive interface, it also allowed greater flexibility during the grinding process.

Any further machine upgrades or diagnosis are also made easier by incorporating a modem which allows secure remote access to the machine software.

The entire commissioning process, including the rewiring of the entire machine, the refurbishment of all ancillary systems, tuning of all axes and the testing of all grinding cycles, was performed in a six week period of down-time.

Full production was able to begin immediately after this commissioning period.

Reductions in grinding time of up to 40% have been experienced on the refurbished machine.

And importantly, operator interaction has been reduced, increasing efficiency and allowing the operators more time to perform other tasks.

Overall, both management and operators at the David Brown plant are extremely happy with the result of the project.

Not only have productivity and usability been improved, but the future viability of the Pfauter Kapp is assured at a fraction of the price of a new machine