Thus, the honing is excellent in spreadability in the stroke direction but poor in spreadability in the circumferential direction. On the other hand, the wave cut is excellent in spreadability in the circumferential direction due to the wave effect, and it can be concluded that the spreadability in the circumferential direction with the wave cut together with oil groove is further accelerated due to the effect of the oil groove.
Regarding the characteristics of the spreadability with the wave cut and the honing, the oil quantity to be carried to TDC is large since the spreadability in the circumferential direction is poor as illustrated in Fig.10, and the spread width is large only at TDC, while the spreadability in the circumferential direction of substantially uniform width from a lower part of the stroke can be obtained with the wave cut.
3.2 Influence of position of oil-feed holes and number of oil-feed holes
Fig.11 shows the comparison in the position of the oil-feed holes and the number of the oil-feed holes. The order of arrangement spreadability of the number of upper oil-feed holes / the number of lower oil-feed holes is 0/8 ＞ 4/4 ＞ 0/4, and 0/8 with the shortest interval between oil-feed holes is most excellent. 4/4 is also more excellent in spreadability than 0/4; however, since the oil-feed timing is determined by the oil scrape, and thus, the spreadability toward the lower part of the position of the upper oil-feed holes is worse than that with O/8.
Fig.12 shows the spreading condition in the stroke direction and the circumferential direction when the position of the oil-feed holes and the number of the oil-feed holes are different. The spreading condition is less different in the stroke direction, while the spreading condition in the circumferential direction is more excellent with 4/4 and 0/8 than with 0/4, and the effect of increasing the oil feed points in the circumferential direction appears considerably even when the oil feed quantity per hole is reduced to one half. The spreading length in the circumferential direction in Fig.12 indicates that for one oil-feed hole with 0/4, and that for two oil-feed holes with 4/4 and 0/8, respectively.
