• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.12
• /
• pp.1048-1055
• /
• 2002

The problem of generating torch paths for 2D laser cutting of a stock plate nested with a set of free-formed parts is investigated. The objective is to minimize the total length of the torch path starting from a blown depot, then visiting all the given Parts, and retuning back to the depot. A torch Path consists of the depot and Piercing Points each of which is to be specified for cutting a part. The torch path optimization problem is shown to be formulated as an extended version of the standard travelling salesman problem To solve the problem, a hybrid genetic algorithm is proposed. In order to improve the speed of evolution convergence, the algorithm employs a genetic algorithm for global search and a combination of an optimization technique and a genetic algorithm for local optimization. Traditional genetic operators developed for continuous optimization problems are used to effectively deal with the continuous nature of piercing point positions. Computational results are provided to illustrate the validity of the proposed algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.624-627
• /
• 2002

A study on machining electrode for LEO(Light Emitted Diode) mold with shaped end-mill is presented. The electrode machining by shaped end-mill has been used for maximizing the productivity in manufacture of semiconductor mold. However, it has not been researched systematically for many difficulties such as the making of shaped end-mill, generation of tool path due to distinctive tool geometry, and so on. Tool path is generated on the shaped end-mill geometry and cutting force to provide accurate and efficient machining of electrode. The verification program can drive enhancement of productivity, selecting cutting conditions from experiment function of cutting force. Also, compensation of tooting and machina error can make the electrode accurate by modifying tool path. Therefore, the research on machining with shaped end-mill can contribute to enhancement of accuracy and productivity in building semiconductor mold.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.1
• /
• pp.53-64
• /
• 1994

Rouge cutting process takes the major portion of machining operation using NC milling machine. Especially, most of the machining time is spent in this process when molds are machined. Therefore, an efficient algorithm for generating the tool path for rough cutting is suggested in this paper. The first step of the procedure is getting the volume to be machined by applying the Boolean operation on the finished model and the workpiece which have been modeling system. Basic principle of determining machining procedure is that a large tool should be used at the portion of the simple shape while a small tool should be used at the complex portion. This principle is realized by representing the volume to be machined by an octree, which is basically a set of hexahedrons, and matching the proper tools with the given octants. When the tools are matched with the octants, the tool path can be derived at the same time.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.1
• /
• pp.29-37
• /
• 1996

In this study, PC controlled CNC automatic cutting system is developed. Technological introduction of the control process and the computer programming has made possible not only the automatic control for cutting processing unit but also the easy-to-use graphic software that enables the cutting process. This program involves shape part drawing and amendment, pattern reading and saving, reading Autocad file, nesting process, kerf compensation, automatic cutting path generation, NC file conversion and motor control. Software is devided into 3 modules for easy work. First step enables drawing, amendment and pattern making, followed by automatic nesting and cutting path generation with kerf compensation. In the final step, drawing data is transmitted for the resulting automatic cutting processes. This software would be applicated in gas cutting and textile cutting so that it improves the productivity of cutting process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.547-552
• /
• 2003

In mold machining, there are many concave machining regions where chatter and tool deflection occur since MRR (material removal rate) increases as curvature increases even though cutting speed and depth of cut are constant. Boolean operation between stock and tool model is widely used to compute MRR in NC milling simulation. In finish cutting, the side step is reduced to about 0.3mm and tool path length is sometimes over 300m. so Boolean operation takes long computation time and includes much error if the resolution of stock and tool model is larger than the side step. In this paper, curvature of CL(cutter location) surface and side step of tool path is used to compute the feedrate for constant MRR machining. The data structure of CL surface is Z-map generated from NC tool path. The algorithm to get local curvature from discrete data was developed and applied to compute local curvature of CL surface. The side step of tool path was computed by point density map which includes cutter location point density at each grid element. The feedrate computed from curvature and side step is inserted to new tool path to regulate MRR. The resultants wire applied to feedrate optimization system which generates new tool path with feedrate from NC codes for finish cutting. The system was applied to speaker mold machining. The finishing time was reduced to 12.6%. tool wear was reduced from 2mm to 1.1mm and chatter marks and over cut on corner were removed.

• IE interfaces
• /
• v.18 no.3
• /
• pp.247-252
• /
• 2005

In the automated production environment in the present days, the minimization of manual operation becomes a very important factor in increasing the efficiency of the production system. The exit burr produced through the milling operation on the edge of workpiece usually requires manual deburring process to enhance the level of precision of the resulting product. So far, researchers have developed various methods to understand the formation of exit burr in cutting process. One method to analytically identify the formation of exit burr was to use the geometrical information of CAD and CAM data used in automated machining. This method, in turn, generated the information resulting from the analysis such as burr type, cutting region, and exit angle. Up to now, the geometrical data were restricted to the single feature and single path. In this paper, a method to deal with the complicated geometric features such as line segment, arc, hole, and spline will be presented and validated using the field data. This method also deals with the complex workpiece shape which is a combination of multiple features. As for the cutting path, multiple tool path is analyzed in order to simulate the real cutting process. All this analysis is combined into a Windows based software and real data are used to validate the program in the conclusion.

• International Journal of CAD/CAM
• /
• v.5 no.1
• /
• pp.1-10
• /
• 2005

A new approach based on vector field clustering for tool path optimization of 5-axis CNC machining is presented in this paper. The strategy of the approach is to produce an efficient tool path with respect to the optimal cutting direction vector field. The optimal cutting direction maximizes the machining strip width. We use the normalized cut clustering technique to partition the vector field into clusters. The spiral and the zigzag patterns are then applied to generate tool path on the clusters. The iso-scallop method is used for calculating the tool path. Finally, our numerical examples and real cutting experiment show that the tool path generated by the proposed method is more efficient than the tool path generated by the traditional iso-parametric method.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.15 no.5
• /
• pp.79-84
• /
• 2006

In modem manufacturing, many products that have geometrically complicated features, including three-dimensional sculptured surfaces, are designed and produced. In the production of these complex-shaped mechanical components, e.g. automobile dies, molds, and various engineering applications, the ball-end milling process is one of the most widely used NC machining processes that consists of roughing, semi-finishing and finishing. In semi-finishing, cusps remained after roughing according to the used tools that have two patterns of stairs and wave shapes. These cusp shapes have air-cut in cutting and instability caused by high cutting speed that affects the cutting characteristics such as cutting force and tool wear. Cutting characteristics are measured and analyzed through cutting force, FFT analysis of cutting force and tool wear along cutting length according to low tool paths with same metal removal rate. As a results of the experiments, this study suggests the optimal conditions of tool path and cutting direction. This approach for the cutting characteristics of semi-finishing provides a useful aid for the productivity and efficiency improvements of NC machining processes.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.6
• /
• pp.41-46
• /
• 2017

Productivity improvement and cost reduction in the aircraft industry have become major industrial objectives, and improving productivity by reducing machining time has become a key focus. When numerical cutting code is created by CAM software, such as CATIA or UG-NX, it is impossible to control machining feed speed using cutting force changes depending on the machining tool path. However, machining an aircraft engine part from difficult material, such as Inconel 718, takes a long time, and tool chipping or breakage often occurs from forcing the machining path too quickly. This study investigated and verified the reliability of the AdvantEdge production module (PM)using cutting power tests. In particular, diffuser and diffuser case parts were considered, comparing cutting power and machining time using AdvantEdge PM and CATIA.

• Journal of Institute of Control, Robotics and Systems
• /
• v.11 no.9
• /
• pp.802-809
• /
• 2005

A hybrid genetic algorithm is proposed for the problem of generating laser torch paths to cut a stock plate nested with free-formed parts each having a set of sub-parts. In the problem, the total unproductive travel distance of the torch is minimized. The problem is shown to be formulated as a special case of the standard travelling salesman problem. The hybrid genetic algorithm for solving the problem is hierarchically structured: First, it uses a genetic algorithm to find the cutting path f3r the parts and then, based on the obtained cutting path, sequence of sub-parts and their piercing locations are optimally determined by using a combined genetic and heuristic algorithms. This process is repeated until any progress in the total unproductive travel distance is not achieved. Computational results are provided to illustrate the validity of the proposed algorithm.