Research On Reliability Assessment Method Of Engine Cylinder Block Flexible Production Line

Rapid development of motor industry has been the dominant force ofmanufacturing industry in China, engine is the core component of automobile andcylinder block is the critical part of engine. Cylinder block flexible production line inChina widely adopts imported equipments, because of the quality of cylinder blockand processing efficiency. Imported equipments not only have a high price, but alsohinder the development of domestic equipments. In order to enlarge the market ofdomestic equipments, enhance the quality of cylinder block and processing efficiency,it is crucial to promote the reliability level of engine cylinder block flexibleproduction line constituted by domestic equipments.In combination with the national science and technology major specialproject-“Demonstration Project for Car GDI Engine Cylinder Block and HeadFlexible Production Line”, this paper researches the reliability assessment of enginecylinder block flexible production line.The main contents of this paper are as follows:1. Research on modeling method of engine cylinder block flexible productionline based on Petri net. Take a car cylinder block flexible production line as theresearch object, according to the layout and equipments of cylinder block flexibleproduction line, cylinder block’s processing technology, and the cylinder blockflexible production line’s equipments are numerous, take the restriction of state spaceexplosion of Petri net into consideration, establish hierarchical models of cylinderblock flexible production line’s operational processes by selecting top-down modelingapproach and utilizing the Petri net. The established Petri net models include entiretylayer Petri net model, equipment layer Petri net model, and process layer Petri netmodel. The entirety layer establishes macroscopic model of the whole cylinder blockflexible production line’s operational processes. The equipment layer details the statesand movements of entirety layer’s operational processes, and takes example foroperational process Petri net model of rough machine tool group and finish machinetool group to illustrate equipment layer. The process layer details the movements ofequipment layer’s equipments to every process. 2. Research on reliability assessment system analytical method of enginecylinder block flexible production line. According to running characteristic ofcylinder block flexible production line and specific requirements of production line’sreliability assessment criteria, establish a reliability assessment system of cylinderblock flexible production line. Obtain reliability indexes and relevance quantities ofreliability indexes by considering reliability influence factors. The reliability indexesinclude production line availability, equipment availability, expense, and the relevancequantities of reliability indexes include productivity, equipment maintenance rate,equipment failure rate, buffer tolerance. Find the relationship between reliabilityindexes and relevance quantities of reliability indexes based on the collectedreliability data. During the process, establish availability Petri net models of cylinderblock flexible production line’s series part and parallel part, alter parameters ofmodels and analyze availability Petri net models by using SPNP, and get the optimalbuffer tolerance between two equipments according to the relationship amongrelevance quantities of reliability indexes.3. Assess the reliability of engine cylinder block flexible production line.Cylinder block flexible production line is a complex system, assess its reliabilityneeds to consider the whole reliability assessment system of cylinder block flexibleproduction line. There are some hierarchical and fuzzy relations among elements inassessment system, use AHP-fuzzy comprehensive evaluation based on intervaljudgment to assess cylinder block flexible production line’s reliability by consideringreliability indexes and relevance quantities of reliability indexes. According to theeffect degree to production line’s reliability and the membership to assessment levelfrom productivity, equipment maintenance rate, equipment failure rate, buffertolerance, realize the assessment of cylinder block flexible production line’s reliabilityby the equipments scores, and compare the cylinder block flexible production line’sreliability by altering the value of buffer tolerance. Finally analyze the links influencecylinder block flexible production line’s reliability by the influence degree of cylinderblock flexible production line from relevance quantities of reliability indexes andequipments’ scores.