Research On Digital Factory-oriented Shop-floor Logistics Planning For The Assembly Workshop Material Supply System Of Engineering Machinery

Designing of new production lines or upgrade of the existing lines is a challenging problem for the production enterprises due to complexity involved in the development of accurate modeling for new or existing systems. Furthermore, the results obtained from the simplified models of these industries are not suitable to give accurate solutions of their problems. Recently, a new technology, called, digital factory technology is quite useful in industry. It can integrate the designing processes of factory layout, workshop, production lines and products using simulation, evaluation and optimization methods in it. Due to this new technology, the manufacturing process in the virtual space can be tested and it has reduced lot of the time of planning and designing for the production systems.Materials supply system is one of the key functional systems of an assembly line. The design of materials supply system in assembly lines includes materials storage, sorting of materials according to its requirement, distribution of materials to desired assembly station, and many other aspects. It is a complex system and it is hard to model and analyze the whole process analytically. However, materials supply system is an important part of the digital factory technology and analysis of this system is significant. Literature indicates different characteristics and difficulties of analytical modeling of the engineering machinery plants and the materials supply process in different industries. Furthermore, some research describes advantages of the simulation techniques and the application of digital factory, its implementation for analyzing materials supply process in the industries. Therefore, a logistics system design using a simulation method for the materials supply process of a well reputed engineering machinery assembly plant is discussed in this paper. In the current research, an integrated control framework based on theory of constrain for a comprehensive simulation of materials supply system in an assembly shopfloor is proposed. Some of the significant features of the proposed comprehensive modeling and simulation method for the studied materials supply system are illustrated below:(1) A simulation model for materials distribution system of an assembly shopfloor is presented in the current research. The proposed model includes all of the key elements of the materials distribution system including, containers of the materials and inventory of materials near assembly lines etc. A new vehicle dynamic dispatching approach is proposed for workshop environment with transportation constraints. The proposed vehicle dynamic dispatching strategy is adapted to the complex dispatching needs of the vehicle in the real environment with considering the transportation constraints as compared to the common dispatching policies used in the simulation optimization of the dispatching methods in literature. The presented simulation based distribution system design can provide better results as compared to the analytical design methods.(2) A new mode of operation and control method for integrated materials supply system is proposed, and current research also presented the process of materials retrieving from stock area and sorting the materials for distribution in the assembly plant. A hybrid model for this process is proposed by integrating a mathematic model of routing optimization problem for sorting of the multiple operations of the system and a distribution model with uncertain materials demand. Moreover, a simulation based logistics design for integrating sorting and distribution systems is also presented. The results of the proposed hybrid simulation experiments with different control parameters indicate that the proposed method can provide better global system performances.(3) A multi-level modeling and multi-resolution simulation method is introduced due to the difficulties of modeling and hybrid simulation for the integrated materials supply system in the current study. The proposed multi-level and multi-resolution simulation method can provide a reasonable way to model and analyze complex and huge systems. Moreover it can increase the speed of system simulation for massive simulation and optimization search. The span of simulation experiments for integrated materials supply system shows that proposed method can improve the efficiency of simulation based design for complex logistics system.The proposed new method is preliminarily implemented in an engineering machinery assembly plant based on its logistics system design requirements. Results indicate that the proposed method tries to improve the design of the plant. Furthermore, a logistics executive system is developed according to the preliminary results of the design of materials supply system. This logistics execution system further enhances the level of automation, efficiency of operation in the materials supply.