• Title, Summary, Keyword: Assembly

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Development of Automatic Selection of Assembly Direction and Assembly Sequence Correction System (조립 방향 자동 판별 및 조립 순서 자동 수정 시스템 개발)

  • Park, Hong-Seok;Park, Jin-Woo
    • Korean Journal of Computational Design and Engineering
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    • v.18 no.6
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    • pp.417-427
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    • 2013
  • Assembly direction is used in order to confirm the generated assembly sequences in an automatic assembly sequence planning system. Moreover, assembly sequence planners can ascertain the feasibility of a sequence during simulation with assembly direction based in a CAD environment. In other words, assembly direction is essential for sequence optimizing and automatic generation. Based on the importance of assembly direction, this paper proposes a method to select the best direction for the generated assembly sequence using disassembly simulation and geometrical common area between assembled parts. Simultaneously, this idea can be applied to verify the generated assembly sequence. In this paper, the automatic selection of assembly direction and sequence correction system is designed and implemented. The developed algorithms and the implemented system are verified based on case study in the CAD environment.

Application of Bucket Brigades in Assembly Cells for Self Work Balancing (자율적인 밸런싱을 실현하는 Bucket Brigade 기반의 조립셀 운영방식)

  • Koo, Pyung-Hoi
    • IE interfaces
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    • v.22 no.2
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    • pp.144-152
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    • 2009
  • Assembly line has been recognized as an efficient production system in mass production. However, the recent production environment characterized as mass customization urges production managers to transform a long assembly line to a number of short assembly cells. To maximize the utilization of resources in an assembly cell, it is important to have the line balanced. This paper presents a bucket brigade-based assembly cell. Bucket brigade is a way of coordinating workers who progressively perform a set of assembly operations on a flow line. Each worker follows a simple rule: perform assembly operations on a product until the next worker downstream takes it over; then go back to the previous worker upstream to take over a new assembly job. In this way, the line balances itself. The bucket brigade assembly cell is analyzed and compared with traditional assembly lines and general assembly cells. The paper also discusses some prerequisite requirements and limitations when the bucket brigade assembly cells are employed.

On the Generation of Line Balanced Assembly Sequences Based on the Evaluation of Assembly Work Time Using Neural Network (신경회로망기법에 의한 조립작업시간의 추정 및 라인밸런싱을 고려한 조립순서 추론)

  • 신철균;조형석
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.2
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    • pp.339-350
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    • 1994
  • This paper presents a method for automatic generation of line balanced assembly sequences based on disassemblability and proposes a method of evaluating an assembly work time using neural networks. Since a line balancing problem in flexible assembly system requires a sophisticated planning method, reasoning about line balanced assembly sequences is an important field of concern for planning assembly lay-out. For the efficient inference of line balanced assembly sequences, many works have been reported on how to evaluate an assembly work time at each work station. However, most of them have some limitations in that they use cumbersome user query or approximated assembly work time data without considering assembly conditions. To overcome such criticism, this paper proposes a new approach to mathematically verify assembly conditions based on disassemblability. Based upon the results, we present a method of evaluating assembly work time using neural networks. The proposed method provides an effective means of solving the line balancing problem and gives a design guidance of planning assembly lay-out in flexible assembly application. An example study is given to illustrate the concepts and procedure of the proposed scheme.

A Proposal for Generating Good Assembly Sequences by Tournament Tree

  • Tsuboi, Kenji;Matsumoto, Toshiyuki;Shinoda, Shinji;Niwa, Akira
    • Industrial Engineering and Management Systems
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    • v.10 no.2
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    • pp.161-169
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    • 2011
  • In seeking further efficiency in production preparation, it is common to examine assembly sequences using digital manufacturing. The assembly sequences affect the product evaluation, so it is necessary to test several assembly sequences before actual production. However, because selection and testing of assembly sequences depends on the operator's personal experience and intuition, only a small number of assembly sequences are actually tested. Nevertheless, there is a systematic method for generating assembly sequences using a contact-related figure. However, the larger the number of parts, the larger the number of assembly sequences geometric becomes. The purpose of this study is to establish a systematic method of generating efficient assembly sequences regardless of the number of parts. To generate such assembly sequences selectively, a "Tournament Tree," which shows the structure of an assembly sequence, is formulated. Applying the method to assembly sequences of a water valve, good assembly sequences with the same structure as the Tournament Tree are identified. The structure of such a Tournament Tree tends to have fewer steps than the others. As a test, the structure is then applied for a drum cartridge with 38 parts. In all the assembly sequences generated from the contact-related figures, the best assembly sequence is generated by using the Tournament Tree.

STEP-based Algorithms for Extraction and Code Generation of Assembly Information (STEP 기반의 조립정보 추출과 코드 생성 알고리즘)

  • Kim K.S.;Choi H.G.
    • Korean Journal of Computational Design and Engineering
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    • v.10 no.6
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    • pp.412-420
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    • 2005
  • The integration of CAD and CAM is critical for computer aided process planning. Recently, STEP has been emerged and utilized as a product data exchange standard format in CAD/CAM areas. The assembly information consists of assembly component relations, assembly features, assembly directions and mating conditions. The purpose of this study is to develop an efficient algorithm to extract assembly information directly from the STEP based files and to generate automatically assembly process plan from the extracted assembly features. The developed algorithms will generate assembly information codes for STEP(AICS). The results from this study can be a reasonable link between design and manufacturing for developing better CAAPP(Computer-Aided Assembly Process Planning) systems.

A Parallel Sequence Extraction Algorithm for Generating Assembly BOM (조립 BOM 생성을 위한 병렬순서 추출 알고리듬)

  • Yeo, Myung-Koo;Choi, Hoo-Gon;Kim, Kwang-Soo
    • Journal of Korean Institute of Industrial Engineers
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    • v.29 no.1
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    • pp.49-64
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    • 2003
  • Although assembly sequence planning is an essential task in assembly process planning, it is known as one of the most difficult and time consuming jobs because its complexity is increased geometrically when the number of parts in an assembly is increased. The purpose of this study is to develop a more efficient algorithm for generating assembly sequences automatically. By considering subassemblies, a new heuristic method generates a preferred parallel assembly sequence that can be used in robotic assembly systems. A parallel assembly sequence concept provides a new representation scheme for an assembly in which the assembly sequence precedence information is not required. After an user inputs both the directional mating relation information and the mating condition information, an assembly product is divided into subgroups if the product has cut-vertices. Then, a virtual disassembly process is executed to generate alternate parallel assembly sequences with intermediate assembly stability. Through searching parts relations in the virtual disassembly process, stable subassemblies are extracted from translation-free parts along disassembling directions and this extraction continues until no more subassemblies are existed. Also, the arithmetic mean parallelism formula as a preference criterion is adapted to select the best parallel assembly sequence among others. Finally a preferred parallel assembly sequence is converted to an assembly BOM structure. The results from this study can be utilized for developing CAAPP(Computer-Aided Assembly Process Planning) systems as an efficient assembly sequence planning algorithm.

Assembly Unit Determination System for Hull Block Assembly Processes (선각블럭 조립에서의 조립단위 결정시스템 개발에 관한 연구)

  • 조규갑;류광렬;최형림;김성진
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.938-941
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    • 1995
  • This paper is concerned with the determination of assembly unit for hull block assembly processes for shipbuilding. In this study,genetic algorithm is adopted for assembly level allocation and assemaly unit is determined by rule-based reasoning. The criteria to detemine assembly unit is to minimize welding operation time for the block assembly.

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Assembly sequence generation using genetic algorithm (유전자 알고리즘을 이용한 조립순서 추론)

  • 홍대선;조형석
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1267-1270
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    • 1997
  • An assembly sequence is considered to be optimal when it minimizes assembly cost while satisfying assembly constraints. to generate such sequences for robotic assembly, this paper proposes a method using a genetic algorithm (GA). This method denotes an assembly sequence as an individual, which is assigned a fitness related to the assembly cost. Then, a population consisting of a number of individuals evolves to the next generation through genetic operations of crossover and mutation based upon the fitness of the individuals. The population continues to repetitively evolve, and finally the fittest individual and its corresponding assembly sequence is found. Through case study for an electrical relay, the effectiveness of the proposed method is demonstrated. Also, the performance is evaluated by-comparing with those of previously presented approaches such as a neural-netowork-based method and a simulated annealing method.

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A Knowledge-based System for Assembly Process Planning (조립 공정계획을 위한 지식기반 시스템)

  • Park, Hong-Seok;Son, Seok-Bae
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.5
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    • pp.29-39
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    • 1999
  • Many industrial products can be assembled in various sequences of assembly operations. To save time and cost in assembly process and to increase the quality of products, it is very important to choose an optimal assembly sequence. In this paper, we propose a methodology that generates an optimal assembly sequence by using the knowledge of experts. First, a product is divided into several sub-assemblies. Next, the disassembly sequences of sub-assembly are generated using disassembly rules and special information can be extracted through the disassembly process. By combining every assembly sequence of sub-assemblies, we can generate all the possible assembly sequences of a product. Finally, the expert system evaluates all the possible assembly sequences and finds an optimal assembly sequence. It can be achieved under consideration of the parameters such as assembly operation, tool change, safety of part. basepart location, setup change, distance, and orientation. The developed system is applied to UBR(Unit Bath Room) example.

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Generation of Robotic Assembly Aequences with Consideration of Line Balancing Using a Simulated Annealing (조립라인의 밸런싱을 고려한 자동 조립 순서 추론)

  • Hong, Dae-Seon;Jo, Hyeong-Seok
    • Journal of Institute of Control, Robotics and Systems
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    • v.1 no.2
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    • pp.112-118
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    • 1995
  • In designing assembly lines, it is required that the lines should not only meet the demand of the product, but also minimize the assembly cost associated with the line. For such a purpose, numerous research efforts have been made on either the assembly sequence generation or the assembly line balancing. However, the works dealing with both the research problems have been seldom reported in literature. When assembly sequences are generated without consideration of line balancing, additional cost may be incurred, because the sequences may not guarantee the minimum number of workstations. Therefore, it is essential to consider line balancing in the generation of cost-effective assembly sequences. To incorporate the two research problems into one, this paper treats a single-model and deterministic (SMD) assembly line balancing (ALB) problem, and proposes a new method for generating line-balanced robotic assembly sequences by using a simulated annealing. In this method, an energy function is derived in consideration of the satisfaction of assembly constraints, and the minimization of both the assembly cost and the idle time. Then, the energy function is iteratively minimized and occasionally perturbed by the simulated annealing. When no further change in energy occurs, an assembly sequence with consideration of line balancing is finally found. To show the effectiveness of the proposed scheme, a case study for an electrical relay is presented.

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