Patent ID: 8247061

Claim:
An annular body, comprising a closed ring of partially crystalline or thermoplastic plastic material, wherein the closed ring constitutes one of a slide bearing bush of a slide bearing and a guide ring for a piston of a piston pump, wherein the annular body has a smooth inner surface, and wherein the inner surface is calibrated without plastic deformation of the plastic material by a process comprising the steps of: inserting the annular body into a receiving device; introducing of an oscillating body into an interior of the annular body with axial advancement with simultaneous excitation of the oscillating body to mechanical oscillations; locally heating the annular body to at least a glass transition temperature of its material by mechanical transmission of these oscillations to the annular body to effect a smoothing of the inner surface by forcing softened material partly into existing adjacent irregularities and pores in the material; continuing axial introduction of the oscillating body until a calibration portion of the oscillating body plunges into the annular body; cooling the annular body to a temperature below the glass transition temperature of its material; and optionally removing the annular body from the receiving device after a retraction of the oscillating body.