| 摘要 |
PURPOSE:To improve the accuracy of roundness in a cylinder bore ever so better, by honing this cylinder bore while cooling its outer wall surface the widthwise side of a cylinder block. CONSTITUTION:A cover body 16 is attached to the top of a cylinder block 1, closing an opening part of a water jacket 3. Next, a cooling water source is connected to each of holes 6-13 via a pipe line 17, and when cooling water is fed, with pressure, to these holes by a pump or the like, it gets spouting to the water jacket 3, and the cooling water is discharged out of holes 14 and 15. Afterward, a honing head 18 is reciprocated inside a cylinder bore 2 while using a coolant, whereby this cylinder bore 2 is honed. At this time, the cooling water is spouted to the water jacket 3 from these holes 6-13, and since it positively cools wall surfaces 19 and 19 adjoining the injection direction in particular, widthwise expansion of the cylinder block 1 is more checked than that in a longitudinal direction. Accordingly, at the time of honing, a thermal expansion value in both directions becomes almost idential, whereby even if temperature in the cylinder block comes down, an error in roundness of each cylinder bore is made smaller. |
