High performance and versatility at heart of new helical profile grinder

PTG Holroyd Precision has launched what it believes to be the world’s most versatile, ultra-high-performance machine for the precision grinding of helical profiles used across the air and refrigeration compressor industry. Called the HG500, the machine meets the needs of manufacturers with varying production requirements, including some of the largest helical rotors used in refrigeration and air-compressor manufacturing. The HG500 will rough- and finish-grind rotors as small as 50 mm in diameter, right up to a maximum 510 mm in diameter, 130 mm profile depth and 1,500 kg in weight.

“Talking to customers following the recent upgrade to our TG series thread grinding machines, we realised that a very real demand also existed for a new large-capacity helical rotor grinder,” says PTG Holroyd’s Sales Director Mark Curran. “Through the HG500, we’ve not only built a machine that’s able to produce a wide variety of rotor sizes but, more importantly, one that can also accommodate the largest, most energy-efficient helical profiles.”

Maximum flexibility in production strategies

When specified in standard form, the HG500 can utilise either a 500 mm vitrified dressable aluminium oxide grinding wheel for flexibility in production strategies and product development, or use plated CBN roughing and finishing wheels for cost-effective volume production. Alternatively, for manufacturers that precision-grind the largest of helical components, a 600 mm vitrified dressable aluminium oxide grinding wheel option is available to help maximise wheel life.

As well as ensuring considerable flexibility in the HG500’s rotor production capability, providing powerful, intuitive programming was also a key objective of PTG Holroyd’s design team – something achieved through the use of Siemens’ SINUMERIK ONE CNC. PTG Holroyd was the first machine tool manufacturer in the UK to embrace the features of the new Siemens CNC, having deployed the control on its HG350 machines and, more recently, on its TG series of rotor and thread grinders.

CNC tailored to precise needs

“Being first to use SINUMERIK ONE presented the opportunity to collaborate with Siemens in tailoring the CNC’s capability to our needs,” says Curran. “The result is robust integrated safety and failsafe features, enhanced reporting of machine health and performance data, and uncompromising levels of industrial security.”

Enhanced connectivity and performance are provided via additional PROFINET and OPC UA interfaces, all made possible thanks to a PLC that is up to 10 times faster than earlier Siemens controls.

Renishaw probe and other features

To enable optimal probing strategies on even the longest of components from the on-board Renishaw OSP60 scanning probe with SPRINT technology, the HG500 uses a travelling grinding head instead of a conventional grinding table. Variable-frequency cooling from a high-pressure unit with wheel scrub ensures efficient coolant usage, while intelligent, programmable eco modes minimise energy consumption between manufacturing cycles.

“In addition to developing what we believe is the most flexible, highly efficient machine for ultra-precise large and small rotor production, we’ve also ensured that the HG500 is extremely intuitive to set up and run,” he says. “Rapid set up of same component batches is delivered via the HG500’s data and program files, while the machine’s CNC-controlled dressing system provides automatic wheel profile correction for each dress cycle, along with programmable dressing feed rates for roughing and finishing.”

Holroyd Profile Management System (HPMS)

Integrated as standard with the HG500, PTG Holroyd’s profile development tool, the Holroyd Profile Management System (HPMS), comprises a suite of programs that enable the straightforward manipulation and analysis of profiles.

HPMS is used in the development and control of a wide range of helical profiles for screw rotors, vacuum and pump screws. The system can also assist the control of a profile during production and provides automatic, in-cycle profile updates and dresser path corrections, in-process lead and profile measurement, and CBN wheel adjustment and correction.