• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.60-68
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• 2007

This paper presents an efficient 5-axis roughing method for centrifugal impeller. The efficient roughing is minimization of cutting time through minimizing tool tilting and rotating motions. To minimized cutting time, machining area is divided into sub-cutting regions using control points on hub curves and shroud curves of blade used to design and analyze centrifugal impeller. For sub-cutting regions, diameters of cutting tools are determined as big as possible. Then, tool paths are generated with the tilting axis and rotating axis of 5-axis machine limited and fixed, which can give more efficient machining speed and machining stability than the conventional methods. Experimental results show that the proposed method is more efficient than the conventional methods to mill with the only one cutting tool without dividing area and the previous methods to mill with simultaneous 5-axis processing with dividing area.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.4
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• pp.7-13
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• 2009

Five-axis laser cutting has great advantages when it is applied to 3-dimensional machining requiring high cutting quality. For developing 5-axis CNC laser cutting systems, however, many problems such as rotating a laser head or a working table, 5-axis servo-control mechanism, tool path generation and post processing, and collision avoidance between a laser head and a work-piece should be solved. In this paper, we deal with developing a dedicated CAM system based on UG-NX3 for 5-axis laser cutting machine. Two essential modules such as post-processor and cutting motion simulation was developed. The developed system was applied to cutting curve defined on 3-D workpiece in order to show the validity of the proposed methods.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.19-27
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• 1997

This paper presents rough cut tool path planning for the fewer-axis machine consisting of a three-axis CNC machine and a rotary indexing table. In the problem dealt with in this paper, the tool orientation is "intermediately" changed, distinguished from the conventional problem where the tool orientation is assumed to be fixed. The developed rough cut path planning algorithm tries to minimize the number of tool orientation (setup) changes together with tool changes and the machining time for the rough cut by the four procedures: a) decomposition of the machining area based on the possibility of tool interference (via convex hull operation), b) determination of the optimal tool size and orientation (via network graph theory and branch-and bound algorithm), c) generation of tool path for the tool and orientation (based on zig-zag pattern), and d) feedrate adjustment to maintain the cutting force at an operation level (based on average cutting force). The developed algorithms are validated via computer simulations, and can be also used in pure fiveaxis machining environment without modification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.335-336
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• 2008

• Korean Journal of Computational Design and Engineering
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• v.14 no.1
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• pp.18-24
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• 2009

This paper proposes an analytical method of evaluating the maximum error by modeling the exact tool path for the tool traverse singular region in five-axis machining. It is known that the NC data from the inverse kinematics transformation of 5-axis machining can generate singular positions where incoherent movements of the rotary axes can appear. These lead to unexpected errors and abrupt operations, resulting in scoring on the machined surface. To resolve this problem, previous methods have calculated several tool positions during a singular operation, using inverse kinematics equations to predict tool trajectory and approximate the maximum error. This type of numerical approach, configuring the tool trajectory, requires much computation time to obtain a sufficient number of tool positions in a region. We have derived an analytical equation for the tool trajectory in a singular area by modeling the tool operation into a linear and a nonlinear part that is a general form of the tool trajectory in the singular area and that is suitable for all types of five-axis machine tools. In addition, we have evaluated the maximum tool-path error exactly, using our analytical model. Our algorithm can be used to modify NC data, making the operation smoother and bringing any errors to within tolerance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.97-103
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• 2013

This study proposes a path generation technique for simultaneous five-axis driving for ball bar measurement, which is equivalent to cone frustum machining as mentioned in the NAS979 standard. The technique is generalized for a 3D circular path, and it is applicable to all machine tools regardless of their structural configurations. A mathematical machine input model that consists of a five-axis machine tool, ball-bar measurement and conical path information as inputs is presented for easy NC code generation, simulation for various test conditions, and a measurement test. The movement range of rotary axes, which depends on various conditions, is mathematically analyzed based on the proposed conical path model. Moreover, the effect of the movement range on various conditions (apex angle and inclination angle, ball bar tilting acceptance angle, offset position of workpiece ball, etc.) is analyzed.

• Transactions of Materials Processing
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• v.23 no.1
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• pp.16-22
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• 2014

The current study presents a simple setup method for making teeth models using a three-axis CNC milling machine. Physical teeth models can be made by several methods: casting, machining, and three-dimensional printing. Since the shape of a teeth model requires five-axis machining, the machining of a teeth model using a three-axis CNC milling machine requires careful setup operations. In this paper a simple datum shape is designed within the work piece of the teeth model. The datum shape is an n-sided prism with regular n-polygon ends and rectangular sides. In the present study a 12-sided prism is used, which easily makes 30 degree rotations for finish machining. The proposed setup approach does not require any special tools for making the teeth model using a three-axis CNC milling machine. A test was run and the results show that the proposed approach is useful for experimental makings with the limited facilities available.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.869-874
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• 2004

The inverse kinematics of five-axis milling machines produce large errors near stationary points of the required surface. When the tool travels cross or around the point the rotation angles may jump considerably leading to unexpected deviations from the prescribed trajectories. We propose three new algorithms to repair the trajectories by adjusting the rotation angles in such a way that the kinematics error is minimized. Given the tool orientations and the inverse kinematics of the machine, we first eliminate the jumping angles exceeding ${\pi}$ by using the angle adjustment algorithm, leaving the jumps less than ${\pi}$ to be further optimized. Next, we propose to apply an angle switching algorithm to compute the rotations and identify an optimized sequence of rotations by the shortest path scheme. Further error reduction is accomplished by the angle insertion algorithm based an o special interpolation to obtain the required rotations near the singularity. We have verified the algorithms by five-axis milling machines, namely, MAHO600E at the CIM Lab of Asian Institute of Technology and HERMLE UWF902H at the CIM Lab of Kasetsart University.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.8
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• pp.705-711
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• 2015

Five-Axis machines can generate undesirable defects such as the undercutting and overcutting errors that frequently occur in the three-axis machining process. It is therefore necessary to develop a program for NC-code generation, whereby the cutter posture is considered to decrease the occurrence of defects. In previous studies, the Easy-Impeller CAM(E-ICAM), an automatic CAM program used for the five-axis machining of impellers, was developed; however, when E-ICAM is used to machine an impeller, it is possible to gouge the hub and blade. Therefore, the aim of this study is the establishment of a formula for each type of endmill to minimize gouging according to the cutter posture, in consideration of several factors that affect accuracy in the machining of an impeller. This study also aimed to improve the performance and accuracy of E-ICAM in the manufacturing of impellers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.783-790
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• 2013

Circular path generation for ball bar measurement using the simultaneous movement of two axes with at least one rotary axis requires the execution of CAM software. However, a change in the machine type or measurement condition requires a new execution of the CAM software, which is cumbersome. This paper presents a circular path generation technique that does not require CAM software and is applicable to different types of driving axes with an arbitrary structural configuration of machine tools and any ball bar setup condition. Mathematical equations are derived for three cases using the proposed technique. In addition, to inspect the measurement feasibility for avoiding physical interference among the ball bar parts, a tilting angle calculation is proposed. The validity of the proposed technique was verified by performing a ball bar experiment with A and C as the simultaneous axes of a five-axis machine tool.