Junker develops all-in-one grinding machine for rotor shafts

Junker‘s flexible and efficient machine concepts result in top quality and highly productive machin-ing. (Source: Junker)

Junker developed new technologies that allow the complete grinding of screw compressor shafts in highest precision.

As a world market leader in grinding with CBN, Junker provides a new milestone in rotor shaft manufacturing. As a partner for precision, Junker simplified processes and developed a flexible and efficient grinding machine concept that provides highest quality with in-process measuring of all critical dimensions — including form scanning and automatic shape correction.

Sullair LLC in Michigan City, Indiana, a Junker customer since 2011 has changed its finishing process to eliminate the demand to pair shafts and achieve highest compressor efficiency. In the past, the process required multiple grinding machine setups to finish a shaft. Diameters and faces of the shaft were ground on the Junker Quickpoint prior to grinding the compressor flutes on form grinding machines. Today, with the JUMAT 6L, all of this is done in one setup and one machine. In addition, for faster changeovers and to control process quality, the machine in-process measuring systems measure key features and automatically adjust the process to produce highest quality without operator intervention. Junker developed the capability to measure the complex compressor flute profile and correct the dressing path to dress the CBN wheels completely automatically.

The correction is essential as tool pressure varies depending on the contact zone of the shape. It is necessary to apply a wheel with an incorrect shape to make a perfect part. The Junker grinding machine masters this with ease, and for optimum accuracy the machine produces parts with a total lead variation of +/- 3 microns and a profile accuracy of less than 6 microns.

For the different flute shapes and for rough and finish grinding, the machine is equipped with a wheel changer. The machine programs call up the correct wheels and manage their life span. If a wheel has reached the end of its life, the controller requests a new wheel and alerts the produc-tion manager to purchase a new one. The parts are presented to the machine on a conveyor with an autonomy of a full shift. Parts are loaded into the machine by an internal gantry system. .

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