• 한국CDE학회논문집
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• 제6권4호
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• pp.244-253
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• 2001

For more complete process planning, machining sequence determination is critical to attain machining economics. Although many studies have been conducted in recent years, most of them suggests the non-unique machining sequences. When the tool approach directions(TAD) are considered fur a feature, both machining time and number of setups can be reduced. Then, the unique machining sequence can be extracted from alternate(non-unique) sequences by minimizing the idle time between operations within a sequence. This study develops an algorithm to generate the best machining sequence for composite prismatic features in a vertical milling operation. The algorithm contains five steps to produce an unique sequence: a precedence relation matrix(PRM) development, tool approach direction determination, machining time calculation, alternate machining sequence generation, and finally, best machining sequence generation with idle times. As a result, the study shows that the algorithm is effective for a given composite feature and can be applicable fur other prismatic parts.

• 한국CDE학회논문집
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• 제6권4호
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• pp.263-270
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• 2001

In stamping-die manufacturing, the first step is to build die patterns for lost wax casting process. A recent industry trend is to manufacture the die pattern using 3-axis NC machining. This study identifies technical considerations of the pattern machining caused by the characteristics of Styrofoam material, and proposes technical methods related to establishing a process plan and generating tool paths for optimizing the pattern machining. In this paper, the process plan includes the fellowing three items: 1) deter-mining a global machining sequence-a sequence of profile, top, bottom machining and two set-ups, 2) extracting machining features from a pattern model and merging them, and 3) determining a machining sequence of machining features. To each machining feature, this study determines the machining start point, generates the approach tool path, and proposes a tool path linking method fur reducing the distance of the cutter rapid motion. Finally, a smooth tool path generation and an automatic feedrate adjustment (AFA) method are introduced far raising the machining efficiency.

• 산업공학
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• 제12권2호
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• pp.346-353
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• 1999

In this paper, the optimum drilling operation sequence which results into the minimum overall machining time required to produce a (multi-diameter) hole is identified. The operation sequence is defined as the set of ordered operations used for producing a (multi-diameter) hole. The overall machining time is derived by summing the minimum machining times of each operation assigned to a sequence. The operations represent the drilling actions of certain sizes to produce the related holes. The minimum machining time of each operation is obtained by solving the optimization problem. Finally, this paper will identify the effects of machining constraints on the overall machining times and their relationships to sequence selection.

• 대한산업공학회지
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• 제21권1호
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• pp.51-65
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• 1995

This paper presents an automatic fixture planning system for machining processes of prismatic parts. A rationalized approach to integrate fixture planning with process planning is proposed and representation schemes for workpiece, part design information with features, machine tools, cutting tools and fixtures are developed. The proposed system implements two activities of fixture planning such as machining of reference surfaces and machining of features. For machining of reference surfaces, the machining sequence of reference surfaces is determined by using decision tables, which are drawn from relations of part dimension, degree of surface roughness, fixture type and its capacity, cutting tool's capacity and experienced planners' knowledge. For machining of features, a preferential machining orientation is selected for its feature which can be machined in more than one direction, and features with the same machining orientation are grouped, and the machining sequence of features is determined by interactive mode. A case study is performed to show the performance of the proposed system.

• 한국정밀공학회지
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• 제15권9호
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• pp.101-110
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• 1998

In process planning for 3D pocket machining, the critical issues for the optimal process planning are the generation of cutting layers and the tool selection for each cutting layers as well as the other factors such as the determination of machining types, tool path, etc. This paper describes the optimal tool selection on a single cutting layer for 2D pocket machining, the generation of cutting layers for 3D pocket machining, the determination of the thickness of each cutting layers, the determination of the tool combinations for each cutting layers and also the development of an algorithm for determining the machining sequence which reduces the number of tool exchanges, which are based on the backward approach. The branch and bound method is applied to select the optimal tools for each cutting layer, and an algorithmic procedure is developed to determine the machining sequence consisting of the pairs of the cutting layers and cutting tools to be used in the same operation.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.642-648
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• 2016

3차원 솔리드모델링이 일반화되면서 이를 이용한 여러 응용이 가능해졌으며, 가장 대표적인 응용분야인 CAM과의 통합을 위한 다양한 연구가 진행되어왔다. 그 결과 설계된 부품의 CAD모델로부터 실제가공에 필요한 특징형상을 자동으로 인식하는 기술들이 개발되었다. 하지만 이러한 방법으로 인식된 특징형상들을 이용하여 절삭가공순서 등을 자동으로 생성하기 위해서는 고려하여야 할 가공순서의 조합의 수가 너무 많아 이를 구현하기에는 현실적으로 문제가 발생한다. 이에 본 연구에서는 절삭가공에 관련된 규칙을 수집하고 이를 이용하여 특징형상 간 가공우선순위를 적용함으로써 고려하여할 조합의 수를 대폭 감소시키고, 이들 조합으로부터 효율성을 최대화 하는 가공순서를 결정하는 방법을 제안하였다. 또한 항공기 부품에 대한 테스트를 통하여 20개의 특징형상으로부터 가공시간이 적은 가공순서를 자동으로 생성할 수 있었다.

• 산업공학
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• 제5권1호
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• pp.3-14
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• 1992

This paper deals with the development of setup planning for Automated FIXture planning system(AFIX) which selects setups, setup sequence and operation sequence in each setup according to the machining mode. In AFIX, part type considered is prismatic workpiece that use the 3-2-1 locating system as the general structure of the fixture. The heuristic algorithms selecting setup and setup sequence are based on DDR(Degree of Dimensional Relationship), AMV(Admissible Misalignment Value) and machining sterategy and feature attributes. A case example is given to illustrate the performance fo AFIX.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.209-213
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• 1998

This study considers flowshop scheduling problem related to flexible maufacturing cell in which consists of two machining centers, robots for loading/unloading, and an automated guided vehicle(AGV) for material handling between two machining centers. Because no machinng center has buffer storage for work in process, a machining center can not release a finished job until the empty AGV is available at that machining center. While the AGV cannot tranfer an unfinished job to a machining center until the machining center empty. In this paper, an new heuristic algorithm is given to find the sequence that minimize their makespan.

• 한국CDE학회논문집
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• 제9권2호
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• pp.175-182
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• 2004

As a bridge between design and manufacturing, process planning is to generate a sequenced set of instructions to manufacture the specified part. Automatic interpretation of manufacturing information incorporated in the design documentation such as CAD file has been a knotty subject for manufacturing engineers since no current data exchange format for product data provides a perfect interface between heterogeneous systems. The recent neutral data exchange format STEp, standard for the exchange of product model data, includes not only geometry but also technical and managerial information. STEP AP(Application Protocol) 224 is specifically dedicated to the mechanical product definition for process planning using machining features. Given a design information in STEP AP 224 format, process planning can be made without human intervention. This paper describes a method to determine the sequence of machining features by using the machining features and the manufacturing information expressed in STEP AP224.

• 한국CDE학회논문집
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• 제3권3호
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• pp.192-200
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• 1998

Even though most die-maker are using CAD/CAM systems rout NC tool-path generation, “front-end”CAD/CAM technologies have not been fully adapted to sculptured surface machining(SSM) nor are sufficiently utilized in die shops. This gap between die-making industry and CAD/CAM community persists mainly because of the lack of a SSM-process model through which the two groups communicate with each other. Proposed in this paper is a model of SSM-processes which is built around the concepts of machining stages, unit machining operations, and each machining stage is decomposed into a sequence of unit machining operations(UMOs). Identified in the paper are five machining stages and 17 types of UMO. Based on the framework of the proposed model, an example of inner-panel stamping-die machining processes is described in detail.