Precision required for rotor grinding

Thanks to the technologies of Holroyd Precision, a major industrial group in northern China will soon embark on the production of its own range of air ends, helical rotors and screw compressors.

A £1.4m order was secured recently that requires Holroyd Precision to supply one of its helical rotor and thread grinding machines to the customer. The machine, a Holroyd TG 350E, is set for delivery in early 2019, when it will be used to precision-grind helical components of up to 350 mm in diameter and 1795 mm in length.
“We are delighted to have secured this significant order,” comments Holroyd regional sales director, Steven Benn. “Although for commercially sensitive reasons we cannot name the customer, it is particularly rewarding to know that in their quest to achieve the highest levels of precision in rotor manufacture, they recognised the uncompromising levels of accuracy that our technologies offer.
“As we are members of the Manchester-China Forum,” he continues, “securing this significant order also underpins our ongoing drive to strengthen ties between the city and China.”
Equally suited to prototyping, batch and volume production, TG series machines are designed primarily for the finish-grinding of helical screw components such as worm screws and rotors after they have been milled to a rough or semi-finished state. Fully automated on-machine probing provides closed-loop feedback of corrections to the dresser wheel and does not require a high level of operator skill.
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Complete machining of spherical components

The compact, high-precision machine tool Sphero, designed for machining workpieces with spherical forms, has been further developed by Thielenhaus Microfinish into a hybrid solution capable of handling the entire superfinishing process in just one set up.

Thielenhaus has designed an innovative trial machine that can machine spherical workpieces, with the highest demands in terms of fine dimensional accuracy and surface quality.
The workpiece is mounted vertically and is therefore easily accessible for fast changeovers. Thanks to the integrated tool changer with a capacity for up to 10 tools, even complex machining processes can be carried out in a single set up.
The trial machine is based on one that was previously used for the manufacturer’s subcontracting work, and is also equipped with QuattroClean CO2 snow-jet technology that enables workpieces to be cleaned using an environmentally friendly, dry and residue-free method. After cleaning, the machined component is subjected to a scattered light measurement procedure that allows, for example, the shape or the gloss value to be determined.
Workpieces with diameters of up to 75 mm can be machined on the Sphero. The machine is used in the automotive industry for machining the joint heads of wheel suspension and steering components that require a high level of freedom and movement for the associated assembly units. Sphero is also used to produce metallically-sealing valve balls and seating rings for valves in the chemical industry, through which aggressive or very hot media travel. Another application is the axial piston pump found in all fields of hydraulics.
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Grinding advances on show at AMB

The latest Kellenberger 100 concept cylindrical grinding machine featured alongside two Hardinge Super Precision turning and turn/grinding CNC centres on the Hardinge Inc stand at the recent AMB 2018 exhibition in Stuttgart.

Since its introduction in 2017, the Kellenberger 100 concept has been well received. While adopting a modular design, the machine makes use of technology from Kellenberger’s Vista and Vita machine ranges, the Tschudin T25, and the Jones & Shipman Ultramat CNC and Ultragrind 1000.
In terms of functionality, the 100 concept delivers a range of configuration options. Modular construction based on a common platform is designed to reduce machine build time yet accommodate numerous ‘standard’ options with an attractive price/performance ratio for the end user.
Three important features distinguish the new 100 machine series. First, a collision-free, compact wheel-head solution with integral motor spindles and a reinforced casing for larger wheel diameters when internal grinding. There is a choice of 10 wheel-head variations to ensure the optimal machine configuration based on the components to be processed.
Secondly, the enhancement of performance parameters. A higher grinding wheel drive power increases productivity while the newly designed Z guideway produces higher profile precision from the C axis, again enhancing precision when non-circular grinding.
Finally, the service-friendly machine concept. Kellenberger’s service teams were involved in the design and optimisation of the machine. This factor impacts on faster maintenance and service operations while optimum accessibility of maintenance-intensive components is assured.
Kellenberger machines feature the latest Fanuc 31i CNC controls with 19″ touch-screen guidance system on an operator friendly, intuitive touch-screen panel. An option is the newly designed cycle programming or workpiece-related graphic programming.
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Schunk boosts wheel handling

Haas Schleifmaschinen is expanding the range of possibilities of its Multigrind CA and CB grinding machines with a fully automated compact storage rack for up to 70 grinding wheels and 20 coolant protectors. A pre-finished linear axis system from Schunk is the key to flexible grinding wheel handling in minimum space.

Using the Schunk system, the shortest changeover time for an individual combination of wheel and protector within the storage rack (during processing time) is just 28 seconds, while the actual change on to the machine is carried out in a time of 10 seconds. Furthermore, milling cutters can be handled using the system, helping users to machine small contours or radii that cannot be reached with grinding wheels. As a safety door interface separates the machine from the storage rack (to protect it from oil mist), a shuttle table is used instead of the conventional machine tool changer.
The interfering contour-optimised axis system was designed by Schunk, and includes valve terminals, cable tracks and the connection to central lubrication. Two multi-tooth guided Schunk PGN-plus universal grippers take on the varied handling of the grinding wheels and coolant protectors. The gripping technology ensures that the tools are safely held in the event of a power failure.
With the aid of a Schunk swivel unit SRU-plus, the bottom gripper can be used both in combination with grinding wheel and coolant protector, and for removing and filling the individual grinding wheels and milling cutters.
In the Z-direction, a Schunk Delta 240C spindle axis is used, which is fitted with a rod lock, extendable spindle and shaft encoder.
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Blank preparation grinder introduced

Capable of achieving a surface finish better than 0.2 Ra with run out of less than 2 µm, the new four-axis Anca CPX Linear blank preparation grinder uses the pinch-peel method of grinding.

Simon Richardson, product manager at Anca, says: “We have taken the best aspects of our technology to build a fantastic machine. For example, our specially designed polymer concrete base provides the utmost stability in our grinding process, so we took that and used it in the CPX Linear model.
“We are known for our ongoing dedication to research, as well as our commitment to ensure that Anca technology surpasses customer needs,” he adds. “This is another major milestone in our approach, providing a complementary machine for the full grinding process. Our customers asked and we listened; designing our own blank preparation machine.”
Anca’s LinX linear motor technology for axis motion (X, Y and V axes), in conjunction with linear scales, is designed for a lifetime of operation in harsh grinding environments. LinX motors have a cylindrical magnetic field, which means there is no additional down force on the rails or machine base.
With no temperature variations (meaning no need for a separate chiller unit), and being sealed to IP67, there is minimal wear and tear so that machine accuracy is retained over the lifetime of the Anca CPX Linear.
With a peak power of 43 kW, the grinding spindle for roughing uses a 250 mm diameter wheel, ensuring high-volume stock removal in a short cycle time. The finishing spindle uses a 150 mm diameter wheel supplying a peak power of 9.7 kW.
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