• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.1-8
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• 2003

Conventionally used linear or circular interpolator is undesirable for the precision machining of 3D free-form surface as the following reason: the transmission errors due to the huge number of data, discontinuity of segmentation, unsmooth motion speed. To this regard, modern CNC machine tools are designed with the function of machining arbitrary parametric curves. However, these systems don't consider the adaptive federate, which dominates the quality of the machining process. This paper proposes a NURBS interpolator for the constant material removal rate. That is accomplished by the variable federate using curvature of curve. The curvature-compensated feederate system has important Potential applications in ensuring part accuracy and protecting cutting tool. The simulated result show it can be applicable to the real machining.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.54-62
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• 1999

This paper describes the design and implementation of a PC(personal computer) based open architecture machine tool controller. The hardware of open architecture CNC has generally a motion control board on a PC for controlling a servo motor. But this paper describes open architecture hardware that consists of a PC, a counter board a DAC board and a DIO board only. This makes it easy to generate CNC software module in a hardware-independent way. The proposed open architecture CNC software runs on the MS-Windows NT. The paper describes a method of con-trolling servo motors using a real-time timer of MS-Windows NT and a commercial real-time operating system on the MS-Windows. NT. An open and reconfigurable software module is made up of an object and an API(application programming interface). Using the object and the API a new CNC system can be quickly configured to control dif-ferent machine tools. The proposed open architecture CNC system is applied to 4-axis lettering center.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.289-296
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• 1997

In this paper, a method has been proposed for error measurement/diagnosis of CNC machine tools using the ball link bar on three dimensional space. For the circular motion error measurement, deviation between the desired and actual test path has been measured and analysed using a new type of ball link which incorporates ideal three point contact between reference balls and sockets. Computer program for the error evaluation has been developed and implemented under PC environment. Using the developed program, the circular test data on a CNC machine tool have been analysed, and thus, machine tool errors were effectively evaluated.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.56-67
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• 1998

This paper introduces a friction compensation fuzzy logic controller, which utilizes a rule-based approach. The paper explains the algorithm of the proposed controller and compares it with a conventional PID controller in simulations and experiments. For the experiments, the two control algorithms were implemented on a 3-axis milling machine in contour milling. These simulation and experimental analyses show that the proposed fuzzy logic controller has superior performance over conventional PID controllers In terms of part contour accuracy.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.111-117
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models the thermal errors for error analysis and develops an on-the-machine measurement system by which the volumetric errors are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments show that the developed system provides a high measuring accuracy, with repeatability of $\pm$2$\mu\textrm{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be also improved by using the developed measurement system when the spherical ball artifact is mounted on a modular fixture.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.684-690
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• 2010

A drum cam with rotational follower has a cam mechanism and it is mainly used in its application such as index table and ATC of machine tool. Also its use can reduce the backlash in its kinematic movement. To machine the drum cam with rotational follower, 5-axis CNC machine tool is generally used and its kinematic principle is included in it's design. Until now, the commercialized CAM software can't cover the application of the drum cam machining. Even if, some special software was developed for machining a drum cam, the post processing method for finish machining was not developed yet. And to overcome the problem, the form tool is still used on the tool path of rough machining. This study includes the induction of the post processing technique for the finish machining of drum cam on three 5-axis CNC machine tools, type AC, AB and BC. To prove the finishing geometric profile, the result was clearly verified through inspection and geometric measurement after direct machining of the drum cam in AC type 5-axis machine tool in this study.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.1
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• pp.53-59
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• 2011

End milling is available for machining the various shape of products and has been widely applied in many manufacturing industries. The quality of products depends on a machine tool performance and machining conditions. Recognition characteristics of the cutting condition is becoming a critical requirement for improving the utilization and flexibility of present-day CNC machine tools. The measurement of tool wear would be performed by coordinate-measuring machine(CMM). However, the usage of CMM requires much time and cost. In order to overcome the difficulties, on-line measurement(OLM) system was applied for a tool wear measurement. This study shows a reliable technique for the reduction of machining error components by developing a system using a CCD camera and machine vision to be able to precisely measure the size of tool wear in flat end milling for CNC machining. The CCD camera and machine vision attached to a CNC machine can determine tool wear quickly and easily.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.4
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• pp.601-611
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• 1998

The machining accuracy of CNC machine tools will decrease the production lead time because the coordinate compensation of the tool path will be unnecessary to meet design specifications. Improving the accuracy of machined parts enhances the reliability and functionality of the assembly as well as the life of the product. Among various factors affecting the accuracy of machined parts, the ambient temperature is the major factor that refers to the temperature surrounding the machine and workpiece. In this study, an experiment was conducted to confirm the dimensional variations caused by changes in the ambient temperature. The ambient temperature resulted in overcutting when it increased. A developed pre-processor converts the CNC program to compensate the dimensional variations caused by temperature changes. This methodology can be used to determine the machining accuracy and improve the positioning accuracy of a machine tool.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1399-1402
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• 1997

Design methodology of Interactuve Measuring Part Program Generating Tools(IMPPGT) realized on the FANUC 15MA using touch trigger probes and interactive macro functions of the CNC was described in this paper. Measuring G codes have been designed according to probe ste up, basic and applied inspection items by using measuring arguments. Menu driven measuring and inspection functions of the IMPPGT were studied and implemented on the CNC through the macro executor and ROM writer. Using the developed measuring G code system on the machine tool, untended measurement and inspection operation was able to be realized in precision FMS lines.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.392-397
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• 1993

Generally machine tools can be divided into three components : NC Controller, the electrical drives and the mechanical transmission elements. For high speed, high precision machining, high performance control of servo system must be accommodated and one must carefully define the interface among three components. In this paper, we suggest a way to assist future development of CNC controller by investigating the characteristics resulting from different interface between CNC controller and servo system.