This machine concept facilitates highly productive profile grinding for large workpieces. The range for external and internal gears comprises models for manufacturing workpieces up to 2,000 millimeters – for industrial gear units, wind power, and marine propulsion applications. Specific and controlled handling of twist in profile grinding solves production-related problems, and simultaneously opens new gear manufacturing doors. Various other solutions are available on the market for dealing with twist problems. Liebherr now introduces the five-axis LFG series profile grinding machines, with a novel machine design approach for twist-free profile grinding (or, if needed, the manufacture of specific twist designs) for single- and double-flank grinding.

Five Axes for Ultimate Precision

The machining concept works with five axes. LFG does not require a dressing axis, which rules out one potential source of inaccuracy. Another difference to comparable machines is the inversion of the shift and swivel axes. The mechanical limitation that results from the process of “first swivel, then shift” is overcome as a result. This special arrangement allows for the dimensioning of shift travel to be much larger than usual. The machine’s directly-driven table, featuring a highly dynamic wear-free torque motor, also delivers high precision throughout the machine’s lifetime. It is a key component in allowing the machine to single- or double-flank grind precision- and custom-topographic tooth flanks.

Simultaneous Dressing Shortens Cycle Times

Because the machine also uses the shift and swivel axes to dress the grinding disks, the dressing axis can be eliminated. The basic LFG model’s grinding disk is dressed by a single dresser in combination with the shift and swivel axes. The Syncdress design provides two dressing rolls that dress simultaneously left and right and greatly reduce dressing time. As a result of its increased importance, the LFG relies greatly on the permanently active swivel axis for profile grinding. Traditionally, the swivel axis was a set-up axis that was pivoted and clamped for grinding purposes. The grinding head for producing internal gears is mounted over the outer grinding head. No contact is made with the outer grinding head. Only the grinding disk must be removed.  The dressing process for the internal grinding disks is consecutive, with the aid of the shift axis. For the expanded product news item, please see the May issue of Gear Technology magazine.