Overload Analysis And Process Optimization Of Milling And Drilling Machining On Automobile Engine Cylinder Block

The cylinder block is the basic component of a engine.Its processing quality directly affects the performance and service life of the engine which is taken as the heart of a vehicle.Processing technologies of automobile engine cylinder contain so many complex technical requirements that some manufacturing problems occur frequently in the cylinder block production line,such as tool abnormal loss,exceeding tolerance range and other common problems.These problems not only decrease the production rate,but increase the costs sharply.This paper aims at analyzing the problem of tool abnormal loss in cylinder block production line.Taking tool machining overload as a cut-in point,milling overload and drilling unusual broken are prominently discussed and studied.This thesis starts with comparative analysis of the material properties and cutting performance of two kinds of cylinder blank,including chemical composition,microstructure,hardness,cutting resistance and other aspects.It reveals the phenomenon of unreasonable content of adding alloy element,uneven microstructure,hardness fluctuation in the casting process of type A cylinder blank.Leading to the conclusion that the cutting performance of type A cylinder blank is inferior to type B cylinder blank.The machining of cylinder block includes surface machining and hole machining.The research on milling process is carried out to analyze the factors of milling overload.The force empirical model changing with the number of milling the cylinder blocks’ rear face is established.Based on the relationship between cutting arc length and milling force,the threshold value of the tool machine is obtained under the comparison of this two types of cylinder.In order to reduce the milling load,the maximum cutting arc length of the machining area is optimized,and the “twice cutting path” plan meeting manufacture rhythm is proposed.The effectiveness of this plan is validated by comparing the spindle motor current value after milling the cylinder blocks’ rear face with two tool paths.The research on drilling process is carried out to analyze the factors of unusual broken-tool.The empirical load models of the straight slot drilling and the auger drilling are established,and the influence level of drilling factors is compared by using Range Method.Based on the method of subsection feeding,the cause of drill breakage is analyzed.It is demonstrated that the chip has great significance on drilling load and cause the drill severely pinched and broken.Machining parameters meeting production rate are optimized on the basic of contrast experiments.