• 한국생산제조학회지
• /
• 제8권3호
• /
• pp.15-22
• /
• 1999

In this study, a machining error estimation system far vertical lathes with structural deformation and geometric errors, is realized based on the virtual manufacturing technologies. The positional and directional errors of cutting tool are determined by considering the geometric errors and dimensions of machine components and by introducing the equilibrium condition between the cutting force and structural deformation. Especially, the machining errors of vertical lathes are estimated by using the prescribed cutting test(JIS B 6331). The system can be implemented to evaluate the machining accuracies of vertical lathes at the design process and to design the high precision vertical lathes.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1998년도 추계학술대회 논문집
• /
• pp.146-151
• /
• 1998

In this study, a machining error estimation system for vertical lathes with structural deformation and geometric errors, is realized based on the virtual manufacturing technologies. The positional and directional errors of cutting tool are determined by considering the geometric errors and dimensions of machine components and by introducing the equilibrium condition between the cutting force and structural deformation. specially, the machining errors of vertical lathes are estimated by using the prescribed cutting test(JIS B 6331). The system can be implemented to evaluate the machining accuracies of vertical lathes at the design process and to design the high precision vertical lathes.

• 대한기계학회논문집
• /
• 제19권1호
• /
• pp.38-44
• /
• 1995

We made a counter to measure the output of motor encoders for the motion error analysis of a CNC machining center, and have measured the dynamic characteristics and the position errors experimentally. Especially, we measured the radius errors for different feedrates and different radii when the CNC machining center performed a circular interpolation. We have also used an iterative learning method to reduce the radius errors and stick motion errors generated by the CNC machining center performing a circular interpolation. The results show that the proposed learning scheme can reduce the radius error and stick motion error significantly. The reduction of errors becomes more pronounced for higher feedrate and smaller radius.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
• /
• pp.214-219
• /
• 2001

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. In this study, the compensation device and temperature-based algorithm have been presented in order to compensate thermal error of machine tools under the real-time. 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, a designed spherical ball artifact, and five gap sensors. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• Journal of Computational Design and Engineering
• /
• 제2권4호
• /
• pp.253-260
• /
• 2015

Feature-based NC machining, which requires high quality of 3D CAD model, is widely used in machining aircraft structural part. However, there has been little research on how to automatically detect the CAD model errors. As a result, the user has to manually check the errors with great effort before NC programming. This paper proposes an automatic CAD model errors detection approach for aircraft structural part. First, the base faces are identified based on the reference directions corresponding to machining coordinate systems. Then, the CAD models are partitioned into multiple local regions based on the base faces. Finally, the CAD model error types are evaluated based on the heuristic rules. A prototype system based on CATIA has been developed to verify the effectiveness of the proposed approach.

• International Journal of Precision Engineering and Manufacturing
• /
• 제5권2호
• /
• pp.60-67
• /
• 2004

For improving the motion accuracy of hydrostatic tables, a corrective machining algorithm is proposed in this paper. The algorithm consists of three main processes. The reverse analysis is performed firstly to estimate the rail profile from the measured linear and angular motion error, in the algorithm. For the next step, the corrective machining information is obtained based upon the estimated rail pronto. Finally, the motion errors on the correctively machined rail are analyzed by using the motion error analysis method. These processes are iterated until the analyzed motion errors are satisfactory within the target accuracy. In order to verify the validity of the algorithm theoretically, the motion errors calculated by the estimated rail after the corrective machining process, are compared with those by the true rail which is previously assumed as the initially measured value. The motion errors calculated using the estimated rail show good agreement with the assumed values, and it is shown that the algorithm is effective in acquiring the corrective machining information to improve the accuracy of hydrostatic tables.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1992년도 추계학술대회 논문집
• /
• pp.34-38
• /
• 1992

Geometry based CAD/CAM system is hard to achieve "net shape machining" For a net shape machining, the machining errors should be compensated by off-line CAD/CAM system followed by on-line control system. In this paper, we investigate an off-line compensation scheme for the machining errors due to tool deflection in contouring operation. The significance of the deflection errors is first shown, and a compensation is sought via modifying the nominal tool path. In modification, tool deflection amount is iteratively compensated until the deflection amount is iteratively compensated until the deflected path results in the desired contour within a tolerance. The path modification algorithm has been tested via computer simulation. The developed algorithm can be used as a postprocessor for the current CAD/CAM system based on geometric modeling as a means for enhancing the machining accuracy.

• 한국공작기계학회논문집
• /
• 제17권2호
• /
• pp.121-127
• /
• 2008

Micro end-milling has been becoming an important machining process to manufacture a number of small products such as micro-devices, bio-chips, micro-patterns and so on. Despite the importance of micro end-milling, many related researches have given grand efforts to micro end-milling phenomenon, for example, micro end-milling mechanism, cutting force modeling and machinability. This paper strongly concerned actual problem, micro tool deflection, which causes excessive machining errors on the workpiece. To solve this problem, machining error prediction method was proposed through a series of test micro cutting and analysis of their SEM images. An iterative algorithm was applied in order to obtain corrected tool path which allows reducing machining errors in spite of tool deflection. Experiments are carried out to validate the proposed approaches. In result, remarkable error reduction could be obtained.

• 한국정밀공학회지
• /
• 제12권2호
• /
• pp.97-111
• /
• 1995

In this paper, we investigate path compensation scheme for the machining errors due to tool deflection in 2D contour machining. The significance of the deflection error is first shown by experiments, and a direct compensation scheme is sought. In the presented scheme, the tool path is evaluated and correcte based on the instantaneous deflection force model, until the desired contour can be obtained under the presence of tool deflection in actual machining. In the sense that the developed method estimates and compensates the machining errors via modifying the tool path, it is distinguished from the previous approach based on geometric simulation and cutting simulation. Further, it can be viewed as a direct and active method toward direct shape control in CNC machining. Simulation results are included to show the validity and adequacy of the path-modification scheme under various cutting conditions.

• 한국생산제조학회지
• /
• 제7권5호
• /
• pp.15-28
• /
• 1998

Recently may investigations have been studied on the high-speed machining by using machine tools. A CNC machine tool makes some tool path errors caused by software acceleration/deceleration. The faster a cutting feedrate is, the bigger the tool path errors are. Some known methods reduce these kinds of errors, but they make the total cutting time increased. This paper presents a feed-forward algorithm that can be generated by distorting the original tool path, and reduces the tool path errors and the total cutting time. The algorithm to generate a new tool path is represented as following; 1)calculating each distance of software acceleration/deceleration between two adjacent blocks, 2) estimating the distorted distance which is the adjacent-ratio-constant(k1, k2) multiply the distance of software acceleration/deceleration, 3) generating a 3-degree Bezier curve approximating the distorted tool path, 4) symmetrically transforming the Bezier curve about the intersection point between two blocks, and 5) connecting the transformed Bezier curve with the original tool path. The algorithm is applied to FANUC 0M. The study is to promote the high-precision machining and to reduce the total cutting time.