Availability Analysis And Optimization Strategies Research Of A Multi-State Cylinder Block Production Line

With the great success of the 40 years of reform and opening,China’s manufacturing industry has not only made important contributions to domestic economic and social development,but has also become a major engine of world economic growth.However,facing the "two-sides" challenges that China’s manufacturing industry poses from the current complex and ever-changing international competitive landscape,as well as industrial changes brought about by a new round of scientific and technological revolution in the future,China’s manufacturing industry must focus on improving the innovation and basic capabilities of the manufacturing industry,promoting the deep integration of information technology and manufacturing technology,and promoting the manufacturing industry toward high-end,smart,green development of service direction,fostering new competitive advantages in manufacturing.As a key link in the automobile manufacturing industry,the cylinder production line is a complex system composed of multiple types of production equipment,such as high-end CNC machine tools,robots,and inspection equipment.In order to ensure the production efficiency of cylinder block processing,the manufacturer has high requirements on the availability of the cylinder block production line and its components;otherwise,the production line suspension due to equipment failure is likely to cause the company to pay huge default losses.Moreover,different equipment has different availability and aging characteristics,so that the cylinder production line has dynamic availability and a tendency to deteriorate during its life cycle.The current research on the availability of cylinder production lines mainly focuses on the steady-state availability of the production line and its equipment,while that on the dynamic availability analysis and optimization of the production line in the lifetime is still blank.In view of the above reasons,this article relies on a major national project to take a domestic engine block production line as the research object,and proposes a dynamic availability analysis method of the cylinder block production line and its component equipment during the life cycle from the perspective of a multi-state system,then two optimization strategies for dynamic availability of the cylinder block production line are proposed based on the evaluation resultsThe thesis mainly completed the following contents(1)Based on the non-homogeneous Markov reward model,a statistical analysis method for evaluating the dynamic availability during the life cycle of the cylinder production line components is proposed.Taking the main production equipment in this production line——machining center as an example to illustrate the feasibility and superiority of the proposed method.This method considers the characteristics of the multi-fault mode of the machining center,and considers that the diversity in the operating state of the machining center during the lifetime is caused by the change of the system module status,then the state transition process of the multi-state machining center is established.Then use NHMRM to calculate the accumulated rewards of the machining center to obtain the dynamic availability of the multi-state machining center.It provides an important basis for the subsequent dynamic availability analysis and optimization of the cylinder block production line(2)Aiming at the "state dimension explosion problem" that is common in the traditional multi-state system analysis process,a method for evaluating the instantaneous availability of the multi-state cylinder block production line based on the Lz-transform method is proposed.This method first establishes the reliability block diagram(RBD)of the cylinder block production line according to its organizational structure and the equipment failure process;then uses the corresponding universal generation operator to integrate the Lz-transform of a component to obtain that of the cylinder block production line based on the RBD,and following quantitatively determine the dynamic availability and corresponding capacity change of the production line under different production capacity requirements,so that the enterprise can arrange reasonable production tasks to complete the order demand.Finally,the importance analysis of the production line is performed to determine the key stations that affect the dynamic availability of the cylinder production line,and prepare for the subsequent research on the optimization of the dynamic availability of the production line(3)Considering the maintenance fact at the production site that the timely maintenance combined with annual minor repairs and random overhauls,with the reliability associated cost(RAC)and the expected availability as constraints,the optimal maintenance plans of key stations are formulated.First use Kijima’s virtual life model and extended periodic incomplete preventive maintenance(EPIPM)model to determine the failure rate of key stations after undergoing preventive maintenance.Then use NHMRM to determine the key station maintenance optimization objective function and following introduce the genetic algorithm(GA)to determine the optimal maintenance plans of the key stations in the life cycle.Finally,a numerical case demonstrates that the proposed strategy is feasible and effective to optimize the dynamic availability of the cylinder block production line(4)Considering the imbalance in production capacity between cylinder block production line stations and the actual situation of no buffer between on-site stations,a method for analyzing the intermediate buffer capacity based on a two-stage stochastic model is proposed to study the impact of the intermediate buffer capacity on the dynamic availability of the aging production equipment,and proposes a reasonable design of the intermediate buffer to achieve the target of dynamic availability optimization of the cylinder production line.The first stage of the two-stage stochastic model is to generate an equivalent processing domain model that is neither blockage nor starvation.In the second stage,the rigid connection of the production line is transformed into a flexible connection for the existence of intermediate buffer,thus a dynamic availability model of the equivalent production line composed of equivalent processing domains is established.Finally,according to the set availability requirements,the capacity buffer design plan of the production line is determined.The results show that a reasonable capacity design of the intermediate buffer has a significant effect on improving the dynamic availability of the cylinder block production lineIn conclusion,by comparing the two strategies to improve the dynamic availability of the cylinder block production line,the better optimization plan is selected,which provides a basis for decision-making on the actual optimization of the availability of the cylinder block production line or the design of a new similar production line layout plan.