Showing papers on "Roller burnishing published in 1990"

Method for the roller burnishing, with straightening, of crankshafts

Abstract: Method for the roller burnishing, with straightening, of crankshafts, consisting in applying rollers under pressure in the shoulders (6, 7, 8, 9, 10, 11, 12) for connecting the bearing surfaces (journals 2, 3 and crankpins 4, 5) of a crankshaft (1) driven in rotation, according to a predetermined profile (pressure, time, number of revolutions), characterised in that the following steps are carried out in succession: - the roller burnishing of all the shoulders for connecting the bearing surfaces of a first type of the crankshaft, according to the said profile, then - a first roller burnishing of all the shoulders for connecting the bearing surfaces of the second type, for a time and a number of revolutions substantially equal to half the values according to the said profile, - the measurement of the sag (deflection) of the crankshaft, and - a second roller burnishing of all the shoulders for connecting the bearing surfaces of the second type, for a time and a number of revolutions substantially equal to half the values according to the said profile, varying the load on the rollers, within the limits of the tolerances of the said profile as a function of the measured sag, so as to straighten the crankshaft.

Roller burnishing tool for effecting diminishing stress reversal on annular workpieces

Abstract: A roller burnishing tool is disclosed having inner and outer pluralities of concentrically disposed, precision tapered rolls. A precision tapered annular mandrel is disposed within the inner plurality of rolls and operates to controllably urge the inner plurality of rolls outwardly against a lip of a workpiece inserted between the inner and outer pluralities of rolls. The inner plurality of rolls forces the lip outwardly into contact with the outer rolls, and the pressurized contact of the rolls effects a burnishing action on the surfaces of the lip of the workpiece. In a preferred embodiment, the burnishing tool also includes a pilot stop for receiving an alignment post used to align the workpiece with the burnishing tool. When the burnishing tool engages the alignment post, the pilot assembly and mandrel are forced inwardly, whereby the tapered mandrel causes the inner rolls to be forced outwardly against an inner surface of the workpiece, thereby forcing the portion of the workpiece being machined outwardly against the outer rolls. The pressurized contact of the rolls effects a burnishing action which helps provide a micro surface finish to the surfaces of the workpiece. In a preferred embodiment of the invention, each inner roll is also spaced approximately midway between its nearest adjacent outer rolls to thereby effect a stress reversal of the workpiece and remove any curl from the workpiece.