Kellenberger, a Hardinge company, offers the Kel-Varia CNC universal cylindrical grinding machines for grinding large, heavy parts and non-round contours. The grinder is capable of processing a range of workpieces and geometries using combinations of cylindrical grinding, OD and ID out-of-round grinding, thread grinding, and jig grinding, all in one setup. The machine also can be used for non-round shapes such as polygons, free contours and eccentric forms with a C-axis option of interpolating the C and X axes. Three sizes are available with distance between centers of 600, 1,000 and 1,500 mm and center heights of 175, 225 and 250 mm, respectively.
The direct-drive workhead offers an variable spindle speed ranging from 1 to 500 rpm, and a maximum weight capacity of 750 Nm/300 kg (660 lbs). Maximum weight is 250 kg (550 lbs) between centers. Hydrostatic guideways provide frictionless grinding for increased accuracy, reduced grinding time and limited wear on grinding wheels. Combined with the direct-drive workhead, the guideways provide part roundness of less than 0.2 micron, non-round contour accuracy of less than 6 micron, internal eccentric bore of less than 4 micron, and straightness of less than 2 micron, the company says.
The swiveling hydrostatic direct-drive B axis is said to provide simultaneous interpolation of the X, Z and B axes with simple programming for a resolution of 0.00002 degree. It enables complete grinding of traditional and complex parts in a single setup. An optional Kel-Set wheel-measuring device determines the wheel-edge or vector to automatically calculate its angular position. A rotary encoder installed on the workhead spindle offers a resolution of 0.00001 degree. The Heidenhain Grindplus control system helps to ensure dynamic non-round and thread grinding operations. More than 28 wheelhead configurations are available with multiple grinding wheels for external, face and internal grinding.
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The grinding machine features a grinding spindle mounted on maintenance-free hybrid roller bearings for high peripheral speeds of as much as 150 m/sec., and in combination with the machine’s CBN high-speed technology, cycle times and setup times can be significantly reduced.