塑性加工における焼付き発生機構の研究 ; 第3報,焼付き発生に及ぼす潤滑油膜厚さの影響

抄録

A critical condition for seizure initiation was examined using an extrusion-type friction testing machine. Paraffinic mineral oils with three grades of viscosity were tested with various oil film thicknesses, using a commercially pure aluminium as the workmetal. The seizure was always initiated near the die exit. The lower the viscosity of oil used and the thinner the applied oil film was, the earlier the critical punch stroke for seizure initiation was. The oil film thickness estimated theoretically in the previous report could not reasonably determine a critical value for the seizure initiation. Furthermore, the oil film thickness at the die exit was recalculated theoretically under the boundary condition of the trapped oil film thickness measured experimentally. As a result, it has been clarified that the critical oil film thickness for the seizure initiation was less than about 0.2μm.