• Special Issue of the Society of Naval Architects of Korea
• /
• 2011.09a
• /
• pp.101-105
• /
• 2011

In most shipbuilding company, cutting procedure is proceed by cutting machine which run by CNC(Computer Numerical Code) data. In our cutting process, all CNC data is created by our nesting post processor system automatically. Among them, in case that cutting piece in the remnant plate, our system creates only one piece CNC data. Because remnant plate is not typical shape, and ship designers don't know remnant plate shape and quantity. In can happen some merit and good point if we modify 1:1 piece NC data by shorten cutting path, reducing cutting time or re-arrangement piece. For modifying cutting data, outside workers have to call to ship designer or have to go to NC control room where control the CNC system and cutting machine. It makes stop work process, and it waste time. In this paper, we introduce a program that can modify and replace 1:1 NC data with continuous or common NC data automatically.

• Journal of the Korean Society of Industry Convergence
• /
• v.7 no.2
• /
• pp.207-213
• /
• 2004

This paper describes the development of Behind-Tape-Reader (BTR) type DNC system using CYBER 180-830 as a central computer and IBM PC-AT cell control computer and NC lathe with FANUC 5T NC controller. In this system, the connection between central computer and cell control computer is done via RS-232C serial interface board, and that between cell control computer and FANUC 5T controller is done via parallel interface board. The software consists of two module, central computer communication module for NC program downloading and status uploading, NC machine running module for NC operating.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.7
• /
• pp.15-21
• /
• 1997

This paper presented a linear motion accuracy by using two-dimensional probe with the master block and the square for NC machine tools. This measuring system could be measured motion error due to numerical control system. The results of measurement and simulation for motion error were similar, and so, this system had enough accuracy to measure a linear motion accuracy for NC machine tools. The experimental results are as follows. 1. This measuring system could be measured motion error due to mumerical control system. 2. The results of measurement and simulation for motion error were similar. 3. This measuring system had enough accuracy to measure a linear motion accuracy for NC machine tools.

• Journal of the KSME
• /
• v.32 no.6
• /
• pp.554-562
• /
• 1992

수치제어(NC : numerical control) 기술은 공장자동화를 위한 중요 기술이다. 우리 산업현장에 공장 자동화가 확장되면서 NC 공작기계, 산업용 로봇, 삼차원 좌표측정기 등의 사용이 매우 증 가되고 있다. 이러한 수치제어용 기계에서는 자동 위치제어를 위하여 길이변위와 회전각도 감 지용 센서인 NC 엔코더가 매우 중요한 부품이다. NC 엔코더에는 선형 엔코더(NC-스케일)와 회전 엔코더가 있으며, 각각 직선운동과 회전운동을 제어하기 위해서 필요한 자동화 부품이다. 그림 1에서는 CNC 위치제어 시스템에서 정확한 위치로 이동을 목표로하여 서보 제어할 때 기 계축의 위치를 감지하는 센서가 NC 엔코더임을 보여주고 있다. 선형 엔코더는 직선운동의 변 위를 감지하며 NC-스케일 이라고도 말한다. 우리나라에서는 아직 엔코더 제작기술을 개발하지 못하여 전량수입에 의존하고 있다. 이러한 NC 엔코더의 수요는 해외 시장뿐만 아니라 국내시 장에서도 급격히 증가되고 있으며 국산화 개발이 시급하다. 이 글에서는 엔코더의 종류별 작동 원리를 설명하고 또한 NC-스케일 제조기술을 개발하기 위하여 실험하였던 결과를 정리하고자 한다.

• Journal of Computational Design and Engineering
• /
• v.2 no.4
• /
• pp.218-232
• /
• 2015

Piecewise linear (G01-based) tool paths generated by CAM systems lack $G_1$ and $G_2$ continuity. The discontinuity causes vibration and unnecessary hesitation during machining. To ensure efficient high-speed machining, a method to improve the continuity of the tool paths is required, such as B-spline fitting that approximates G01 paths with B-spline curves. Conventional B-spline fitting approaches cannot be directly used for tool path B-spline fitting, because they have shortages such as numerical instability, lack of chord error constraint, and lack of assurance of a usable result. Progressive and Iterative Approximation for Least Squares (LSPIA) is an efficient method for data fitting that solves the numerical instability problem. However, it does not consider chord errors and needs more work to ensure ironclad results for commercial applications. In this paper, we use LSPIA method incorporating Energy term (ELSPIA) to avoid the numerical instability, and lower chord errors by using stretching energy term. We implement several algorithm improvements, including (1) an improved technique for initial control point determination over Dominant Point Method, (2) an algorithm that updates foot point parameters as needed, (3) analysis of the degrees of freedom of control points to insert new control points only when needed, (4) chord error refinement using a similar ELSPIA method with the above enhancements. The proposed approach can generate a shape-preserving B-spline curve. Experiments with data analysis and machining tests are presented for verification of quality and efficiency. Comparisons with other known solutions are included to evaluate the worthiness of the proposed solution.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1992.04a
• /
• pp.148-152
• /
• 1992

수치제어(NC: numerical control) 기술은 공장자동화를 위한 중요기술이다. 우리산업현장에 공장 자동화가 확장되면 서 NC 공작기계산업용 로봇, 삼차원 좌표측정기 등의 사용이 매우 증가되고있다. 이러ㅗ한 수치제어용 기계에서는 자동 위치제어를 위하여 길이변위와 회전각도감지용센서인 NC 엔코더가 매우 중요한 부품이다. NC 엔코더에는 선형 엔코더( NC-스케일)와 회전 엔코더가 있으며, 각각 직선운동과 회전운동을 제어하기위해서 필요한 자동화 부품이다. 선형 엔코 더는 직선운동의 변위를 감지하며 NC-스케일 이라고도 말한다. 우리 나라에서는 아직 엔코더 제작기술을 개발하지 못하여 전량수입에의존하고 있다. 이러한 NC 엔코더의 수요는 해외시장뿐만 아니라 국내시장에서도 급격히 증가 되고있으며 국산화 개발이 시급하다. 이 글에서는 NC-스케일 제조기술을 개발함에있어서 연구하였던 참조위치 마크(Rrference Mark)설계 기술을 정리한다.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.5
• /
• pp.852-858
• /
• 2013

In numerical control (NC) machining, a machining error in equipment generally occurs for a variety of reasons. If there is a change in direction in the NC code, the characteristics of the automatic acceleration or deceleration function cause an overlap of each axis of the acceleration and deceleration zones, which in turn causes a shift in the actual processing path. Many studies have been conducted for error calibration of the edge as caused by automatic acceleration or deceleration in NC machining. This paper describes a geometric interpretation of the shape and processing characteristics of the operating NC device. The paper then describes a way to determine a feedrate that achieves the desired tolerance by using linear and parabolic profiles. Experiments were conducted by the validate equations using a three-axis NC machine. The results show that the machining errors were smaller than the machine resolution. The results also clearly demonstrate that the NC machine with the developed system can successfully predict machining errors induced with a change in direction.

• International Journal of Precision Engineering and Manufacturing
• /
• v.2 no.3
• /
• pp.27-33
• /
• 2001

The aim of the present work is to propose a model for Computer Aided programming of numerical Control lathe. This model is based on the concept by features. It has been developed in an Artificial Intelligence environment, that offers a rapidity as well as a precision for NC code elaboration. In this study a pre-processor has been elaborated to study the geometry of turning workpiece. This pre-processor is a hybrid system which combine a module of design by features and a module of features recognition for a piece provided from an other CAD software. Then, we have conceived a processor that is the heart of the CAD/CAM software. The main functions are to study the fixture of the workpiece, to choose automatically manufacturing cycles, to choose automatically cutting tools (the most relevant), to simulate tool path of manufacturing and calculate cutting conditions, end to elaborate a typical manufacturing process. Finally, the system generates the NC program from information delivered by the processor.

• International Journal of CAD/CAM
• /
• v.4 no.1
• /
• pp.47-53
• /
• 2004

The subdivision surface is the limit of recursively refined polyhedral mesh. It is quite intuitive that the multi-resolution feature can be utilized to simplify generation of NC (Numerical Control) tool paths for rough machining. In this paper, a new method of parallel NC tool path generation for subdivision surfaces is presented. The basic idea of the method includes two steps: first, extending G-Buffer to a strip buffer (called S-Buffer) by dividing the working area into strips to generate NC tool paths for objects of large size; second, generating NC tool paths by parallel implementation of S-Buffer based on MPI (Message Passing Interface). Moreover, the recursion depth of the surface can be estimated for a user-specified error tolerance, so we substitute the polyhedral mesh for the limit surface during rough machining. Furthermore, we exploit the locality of S-Buffer and develop a dynamic division and load-balanced strategy to effectively parallelize S-Buffer.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.04b
• /
• pp.463-470
• /
• 1995

설계, 가공, 조립, 검사기술로 대표되는 생산시스템의 근간 기술은 공작기계에 의한 부품가공 소위, 기계 가공 기술이다. 가공에 필요한 NC 프로그램의 효율적인 관리를 위해 이용되던 종래의 DNC(Direct Numerical Control) 는 가공 Cell 의 효율을 높이기 위해, CNC 가공기 및 주변기기에 대한 실시간 감시/제어기능을 가진 분산제어시스템( DNC(Distributed Numerical Control)으로 발전하고있다. 본 연구에서는 이기종 CNC로 이루어진 가공 Cell에 적합 하고, 경제성, 범용성 및 확장성을 고려하여 RS485 Network 및 RS232C를 이용하여각 CNC 공작기계 및 주변기기와 연결 해서 실시간(Real Time) 동시작업(Multi Tasking) 가능한 DNC 시스템을 개발하였다.