Roundness Control for Grinding

Manufacturing Engineering, Feb 2005

Intended for crankshaft orbital grinding applications, this roundness control function for the Fenar L in-process gage system from Marposs Inc. (Auburn Hills, MI) allows checking roundness of a crankshaft main or pin journal diam immediately after grinding without removing the part from the machine.

The system was developed to complement the modern CNC orbital crankpin grinder where the grinder's wheelhead follows the nonconcentric crankpin as it rotates about the crankshaft's main bearing centerline. It can control size on mains and pins, in a range to 25 mm, without mechanical adjustment, permitting reductions in cycle time. It also allows reduction of the size range in production lots through continuous value monitoring by the gage system of part size and cutting speed to within microns/milliseconds.

Using the same gage, a chordal measurement across three contact points can be done with 1-2 part rotations to check roundness after completing the grinding cycle. Data from the gage goes to a PC either within the machine control or off-line, where roundness calculations are done. Measurements are made quickly to find out if part roundness lies within specified limits. Marposs emphasizes that the gage isn't intended to replace final inspection. Circle 202