تحقیق در مورد طراحی شماتیک خط انتقال انعطاف پذیر با استفاده از برنامه ریزی عملیات سلسله مراتبی

This paper proposes an approach to a bidding-based flexible transfer line (FTL) schematic design system. The architecture of the flexible transfer line schematic design system (FTLSDS) is established. The system consists of four processes: part feature modeling, process planning, FTL facility layout and FTL evaluation. For FTL schematic design, a five-level process planning strategy named the hierarchical process planning method is proposed. This method includes the selection of the manufacturing feature machining operation, part set-up planning, feature sequencing, operation sequencing and process plan generating. The major decision relies on set-up planning. The framework of the machine modular design system to support machine requirement design for FTL is implemented. In the process of evaluation, quality, flexibility, reliability, machine load, and cost are taken into account.

The flexible transfer line (FTL) is now used widely in many manufacturing domains to realize efficiently, high quantity and economic production. These manufacturing domains include automobiles, tractors, internal-combustion engines, and so on. In today’s competitive business environment, it is vitally important for machine tool manufacturers to design FTLs more effectively and efficiently according to a wider variety of customer demands. Successful industrial companies must be able to adapt quickly to fast-changing conditions in the market and to competitors within a shorter lead time at a low cost. It is a pre-condition to acquire the FTL order that the manufacturers must provide their customers with the plans of the FTL and an accurate quoted price as quickly as possible. It has been recognized that computer aided process planning (CAPP) plays an important role in an integrated computer aided design (CAD) and computer aided manufacturing (CAM) system. Process planning involves determining the necessary manufacturing processes and their sequence in order to produce a given part economically and competitively. The major process planning activities are the interpretation of product design data, the selection of a part blank, the selection of machining processes, the determination of machine tools, the selection of cutters and fixtures, the sequencing the operations, the determination of cutting parameters, the calculation of overall production times, and the generation of process sheets. There are two main approaches to CAPP, namely the variant approach and the generative approach [1]. The variant approach relies on existing standard plans developed from previously manufactured similar parts, and involves retrieving the plan by a group technology (GT) code and making the necessary modifications to the plan for the new part. The generative approach involves the generation of new process plans automatically by means of decision logic and process knowledge, without referring to previous existing plans. In general, process planning is limited by manufacturing facility resources, but the CAPP for FTL schematic design is different. It first generates a near optimal process plan without regard to facility resources, and then selects machine tools or designs special purpose machine tools by means of the modular design principle. In this paper, a suitable process planning strategy for FTL schematic design is proposed. A design methodology of a manufacturing systems usually can be defined as a set of procedures that analyses and segregates a complex manufacturing system design task into simpler manageable sub-design tasks while still maintaining their links and interdependencies [2]. The FTL design procedure is in the same way. The design procedure includes the following steps: Step 1: requirements of manufacturing system design; Step 2: selection of manufacturing operations; Step 3: selection and design of machine tools; Step 4: design of the manufacturing system configuration; Step 5: design evaluation; Step 6: implementation; and Step 7: re-configuration. This paper describes a bidding-based approach in the integration of part feature modeling, hierarchical process planning and evaluation. Concerning with the research on the methodology of FTL schematic design for prismatic parts using hierarchical process planning, the main objective is to develop a flexible transfer line schematic design system (FTLSDS) which can drastically decrease the FTL development time.

This paper presented an approach to a bidding-based FTLSDS. By using the hierarchical process planning method and blackboard based reasoning, the process planning for an FTL schematic design has been completed. Since the planning is divided into several stages, when conflicts occur at later planning stages, it is convenient for users to return to the foregoing planning stages and make appropriate adjustments. The selection of general machine tools and the modular design of special purpose machine tools are discussed next. Different configurations have profound impact on the performance of an FTL. By synthesizing the five evaluation criteria, users can choose a better configuration. An example is provided to demonstrate and verify the validity and feasibility of the FTL schematic design approach.