ABSTRACT The purpose of this paper is to establish an effective inspection system by using OMM (On-Machine Measurement) system based PC-NC. This system can reduce manufacturing lead time because a workpiece is inspected at every machining process and the manufacturing system which includes inspection faculty is able to realize on-line process on CNC machining center. The proposed OMM system is composed of a few algorithms for determination of inspection parameters. It is accomplished by determining the number of measuring points, their location, measuring path using fuzzy logic, Hammersley’s method, TSP (Traveling Salesperson Problem) algorithm. The inspection feature applied to this system is based on machining feature. This method is tested by simulation and experiment that are analyzed measuring data and geometry tolerance.70604

Key Words: OMM (On-Machine Measurement), CMM (Coordinate Measurement Machine), PC-NC, Inspection, Geometry tolerance

1. Introduction

In general mechanical manufacturing, tool paths of rough cutting and fine cutting are determined by feature data which is generated after executing the modeling of product using CAD/CAM software. Machining  of wanted products is carried out along these tool-paths and then the geometric error of product is determined by using inspection equipment of contact or non-contact type, at this time, errors can be caused by  their equipment but most of errors are still caused by mechanical machining. Besides, nobody knows the current machining is content with the range of tolerance using the current offline system of manufacturing because inspection process of offline system is done after the cutting is finished. If a machine operator can know the information about error of each machining process in processing, a working time and a economic loss can be

reduced because the operator can decide whether the following process will be executed or not with the advance of error, so in halfway the work, operator can deal with error actively. Generally, a CMM (Coordinate Measuring Machine), touch -type equipment, guarantees excellent precision whereas it is impossible to carry out inspection in machining and the inspection time is long. Besides, the error due to coordinate change must be considered because the workpiece is moved from a machine tool to a measuring machine. On the other hand, the proposed OMM (On-Machine Measurement) system can measure the error of each machining process in machining. In this study, an OMM operating system that a user can operate easily and measure the error of manufacturing during machining is developed. In the OMM study of Cho., it is presented the inspection method based on the integration of CAD/CAM/CAI    for

eliciting the condition of inspection efficiently based on the data of CAD.1, 2 The research of modeling of geometric and thermal deformation errors of a machine tool have been progressed actively.3,4,5 In fields of the machine  manufacturing  headed  by  the  production    of

mold, there is requested a greater necessity of OMM which is able to inspect objects on machine. With this necessity, the system of OMM on PC-NC (Personal Computer based Numerical Control) which is oncoming generation numerical control system is made. Because PC-NC can contain CAD/CAM software unlike the current machine tool, software and module which can be operated online are under development. In this study, it was constructed the system that can run the simulation of machining and inspection through the interface and DPROM (dialog CAM program) of the PC-NC operating systems developed by HYUNDAI Motors CO.,  LTD. The existing CAD feature must be adjusted for carrying out the inspection. However, the CAD/CAM/CAI integrated system is built by the classification of inspection feature. The developed system is verified by the simulation and experiment.

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