The Research And Practice Of Large Camshaft Bore Flexible Machining

Camshaft bore hole, as a key position of the diesel engine for gas distribution motion output, its machining-precision has an important effect on engine performance.Since the machining-precision requirement for the camshaft hole is high and the hole is long, it is a typical case for high-precision deep hole machining. Compared to the crankshaft hole, the camshaft hole is also going throughout the cylinder block or cylinder head, but camshaft diameter is smaller, having larger length/diameter ratio,resulting to higher difficulty for machining. Flexibility machining of large diesel engine camshaft hole has become one of the difficulties during new product development stage, due to low production, unfixed product drawings and unavailability of special machine tools. Especially YC6 K appears, this machining problem is going to higher stage during the development of YC6 K diesel cylinder head.In order to understand key factors for the machining quality, this paper is doing research on camshaft hole flexible machining system error theory. In addition, this paper is doing this research base on the YUCHAI flexible machining system, with the purpose to come up with a suitable maching method for large camshaft.Practicical research on camshaft machining for the 6K diesel engine cylinder head has came up with a large hole flexible machining technology: boring the two end gears of camshaft hole in horizontal machining center, then boing the middle three gears in horizontal boring machine, it has proved that this method is feasible.Problems found in practice and solved:(1) the qualified rate can be increased by increasing machining quality for the middle three gears of the camshaft hole;(2) as for wear and tear resulting from the abnormal contact between rocker arm roller and camshaft, fixture principle can be applied to dismounte the camshaft-cap and then machine rocker shaft hole, finally the parallelism between rocker shaft and camshaft can be enhanced, also the wear and tear can be eliminated.(3) In practice, original development of relevant cutter can decrease the costs and the time consumed for the new product development, supporting YC6 K to seize market opportunities.