Latest semi-automatic control provides grinding reliability and performance

For over 40 years, Robbi, based just south of Verona in Italy has been supplying its range of Omicron universal, plain, and internal grinding machines with an easy-to-use interface, that, complete with software, bridges the gap between its conventional and CNC product ranges.

“The new T7 control, first unveiled at MACH 2022 in April takes the Robbi T7 series to new levels in ease-of-use, reliability, and operation,” explains Simon Rood, RK International Machine Tools’ director and general manager.

“Designed for small to medium batch quantities, the T7 software is developed in house at Robbi and operates on the Siemens 840D sl axis controller along with a Siemens drive and servo package.

“Driven by a Siemens motor, the hydrodynamic wheel head spindle not only provides significant advantages over traditional ball bearing spindle designs, but also excels with surface finish performance and rigidity. The machine’s linear axes are powered by the high dynamic, high inertia Siemens 1FK7 brushless servo motors.”

The interface between operator and machine is displayed on the Siemens TP900 with an option to upgrade to the larger TP1200 touchscreen panel, and, although the machine doesn’t feel like a CNC, the control is responsible for the wheel head traverse movement in the X-axis, the table carriage longitudinal movement in the Z-axis, and the workhead spindle speed.

The touchscreen panel displays the worktable and wheelhead positions, spark out time and passes and automatic increments including rough and finish for grinding cycles and stock removal.

With a pedigree of semi-automatic control programming, the T7 control provides near CNC performance with the machine being able to undertake plunge, cylindrical pass and multiple plunge grinding cycles.

“An experienced manual grinder can make the transition to the semi-automatic T7 with comparative ease,” Mr Rood comments. “The machine operator can intervene and modify a program whilst the machine is in cycle. Modifying real-time parameters such as increments, stock removal values for rough and finish grinding, dwell inversion times and spark-out passes are all easily initiated in-process.”

By far, the biggest leap forward with the T7 is the ability to store up to 50 component programs on the machine with a total of 12 diameters per component. Dressing cycles are also programmed via the machine’s touchscreen control panel and include front radius and side dressing of the grinding wheel.

It is also possible to recall the dressing cycle on demand, or re-program within the grinding cycle before the end of the finishing operation. Previous versions of T Series control allowed for pass and plunge on the OD and ID, but the T7 now includes OD and ID facing cycles and OD multi-plunge cycles. It is also possible to set up to two different tool offsets for a simple internal/external grinding operation changeover.

A wide range of machine options enhance the T7 Series including: in-process gauging; internal grinding spindles; process controls such as gap control and automatic grinding wheel balancing; fixed and rotary grinding wheel dressers; and full machine enclosure with mist extraction.

The T7 semi-automatic control can be found on universal and plain Omicron grinding machines up to 8,000mm between centres and 995mm diameter swing over the bed, and internal grinding machines with up to 1,000mm internal grinding capacities by 595mm diameter swing with capacities of up to 4,000kg.

RK International Machine Tools

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