| Crankcase hole is an important structure in the engine,most domestic engine manufacturers are still using the traditional machining method of split cylinder block crankshaft holes,this method requires a separate casting and machining of the cylinder block and crankcase.It led to complex process,high processing costs,and the poor assembly positioning accuracy of crankshaft holes.Also,the engine performance and the service life is limited.Compared to the traditional split processing technology,the process route of laser cracking is simple.The machining operation and the amount of processing equipment can be greatly reduced.While the positioning accuracy between the seats and caps,assembly accuracy,the bearing capacity of crankshaft hole after assembly and anti-shear capacity are greatly improved.So,the cracking technology plays an important role in improving the performance of the engine.The cracking technology can reduce 60% of machining process,25% of equipment investment,35% of tool costs,and 40% of energy,the space and scrap rate can also be reduced,the economic benefits are Considerable.The cranking technology on machining crankshaft holes of cylinder block is general trend.But at present,the level of cracking technology in our country is not mature,some cracking defaults still exist in the production,for example,tearing,cracking failure,falling chips,cracking face deformed,and so on,they influence the products quality stability.In view of the above reasons,the paper takes the vermicular cast iron cylinder block,which is used on MC series of high-power engine in a factory,as the research object,and studies on the cracking process of crankshaft bores.ALFING laser cracking equipment were introduced and analyzed,and the quality problems in the production process were deeply analyzed and tracked.The main content including:(1)The composition characteristics and mechanical properties of MC series engine block,made by vermicular cast iron materials,are presented,the construction of the ALFING laser processing equipment which is used to break crankshaft bore,the cracking process characteristics,technical requirements and typical defects are also introduced in this paper.(2)Introduces the producing process of ALFING high power laser equipment,elaborates the principle of the generation and control of laser,laser marking equipment of a plant are introduced in this study,combined with the equipment the method and process of laser marking were described,the influence of laser pulse parameters on the cracking slot is expounded.(3)The paper researched on the quality problems happened in the cracking production,and took the rate of falling chips as the starting point,introduced the factors leading to the chip-falling through the analysis and optimization process by using Six Sigma quality improvement tools.Identified the key factors leading to the chip-falling and improves them by using brain storm,fishbone diagram tool,and DOE experimental method.Tracked and confirmed the quality status and economic benefits after the improvement.The paper researched and analyzed the typical problems of using cracking technology to separate and machining the crankshaft bores.It plays an important role in improving the MC series of engine quality of a factory and keeping the products at domestic and even the world’s leading position.At the same time,it has certain reference value for the research of laser cracking technology and the manufacture and quality control of the cylinder block crankshaft bore of similar engines... |
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