PURPOSE:To sharply improve the surface roughness without deteriorating the circularity of a work by providing a pressing force control means adjusting the pressing force of a burnishing roller in response to the rotation quantity of the work. CONSTITUTION:When the contact position of a burnishing roller 8 with a journal section or a pin section on a crank shaft W is moved near an oil hole, a signal is fed to the servo valve 11 of a hydraulic cylinder 6 from a control device 13 to open the servo valve 11, and the pressure oil in the cylinder 6 is discharged. The pressing force of the burnishing roller 8 by the hydraulic cylinder 6 is lowered accordingly to continue burnishing. When a load cell 9 detects that the pressing force is lowered by the preset quantity, a signal is fed to the servo valve 11 to close it, when the crank shaft W is further rotated and the contact position of the burnishing roller 8 passes the oil hole, the oil pressure in the cylinder 6 rises, and the surface of the journal section of the pin section is burnished.
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