Earticle

이 논문은 한.중.일 간의 CAD/CAM/CAE 시스템을 서로 비교하면서 미래의 공장자동화 시스템의 국제적인 수준을 가늠해 보고 국내에서 사용하는 시스템과 방법을 소개한 후에 몽골에 적용할 시스템을 제시하기 위한 것이다. 아울러 자동화 시스템의 활성화를 통하여 무인화된 공장경영과 함께 동북아의 산업 발전에 이바지하기 위한 것이다. 특별히 CAE시스템이란 CAD/CAM시스템의 중간에 CAPP, EDB, 해석 및 시뮬레이션 등공정 또는 엔지니어링 분야에 대한 보조적인 지원 시스템이다. 또 넓은 의미의 CAE시스템은 해석뿐 만아니라 간섭체크, 공정계획과 관리 등의 복합 기능을 가지고 있다. CAD/CAM/CAE 시스템은 본 기능 외에 모델링과 공정계획에 따른 리엔지니어링, 기능적인 시뮬레이션과 해석, 체제 시스템 및 모델링에 따른 보간 시스템 등을 포함하며, 이들은 각자 유기적인 관계를 형성하고 있다. 한편, 몽골은 세계 최대의 캐시미어 제품의 생산국이고 Gobi회사는 의류 판매만으로도 연간 수천만 달러의 외화를 획득을 하고 있다. 그러나 디자인이나 품질 면에서 선진국에는 미치지 못하므로 이를 개선하기 위하여 의류용 CAD/CAM 시스템의 도입이 절실히 필요하라고 생각된다.

This paper presents a research on the proposing a new alterative to the traditional manufacturing methods, by using CAD/CAM/CAE system in field of injection mold and employing advanced Computer-Aided Design(CAD) /Computer-Aided Manufacturing (CAM) /Computer-Aided Engineering(CAE) technologies in Korea, China and Japan. It is very easy to design 3D model with unit features by mechanist theory and to modify the model by the parametric design. Data management and CAM/CAE linkage; The type of design matrix is uncoupled design. Abundant option modules of Power Mill make it easy manufacturing, engineering analysis and data management. This work includes steps of (1) Modeling and reengineering concurrent mold manufacturing process planning, (2) Analysis of system functional requirements, (3) System framework design, and (4) System modeling and implementation. Then Mongolia supplies the world market with raw, semi-processed, and finished cashmere. mongolia the first biggest raw casmere producer in the world. Gobi Coperation of Mongolia is the world's fifth largest factory by the capacity of producing dehaired fiber and final cashmere products. Therefore the introduction of CAD/CAM system in Mongolia has emerged as the task of advancing the productives structure of clothing high. and it can be expected that CAD/CAM system will exert an influence upon the improvement of productivity in the closing industry.

The geometry of helical milling cutter with specific cross-section profile is normally generated with form cutter by the toolpath generating method. The general purpose CAD/CAM software can generate the cutter location file of this class of product only by the sculpturing method. To obtain the flexibility of machining process, this paper presents an interference-free toolpath generating method for semi-finish and finish machining of the helical milling cutter. The method for design and machining of the helical milling cutter is established based on the differential geometry and the enveloping theory. In the finish machining of helical milling cutter, the form grinding wheel profile is firstly derived. To reduce the cost and lead time of the generating method with the form-mill cutter for semi-finish machining, a toolpath generating method which combines the advantages of the generating method and sculpturing method was presented. The cutter location uses ball-nose conical end mill is derived according to the geometric characteristics of the enveloping element. The cutting simulations with solid model were performed to verify the proposed toolpath generation method.

This paper presents a new technique to analyze data on the coordinate x, y, z and apply these data to design the motion control to improve the efficiency of the engraving machine so that it can engrave accordingly in 3 dimensions. First, the tool path on the x-y plane is analyzed to be synchronized with the z-axis. The digital data is then sent to the motion control to guide the movement of the engrave point on the x-y plane. Tool path moves along the x-axis with zero degree and different values of the y-axis according to the coordinate of the digital data and the analysis along z-axis to determine the depth for engraving. The depth can be specified from the gray level with the 256 levels of resolution. The data obtained includes the distances on x-axis, y-axis, and z-axis, the acceleration of the engrave point's movement, and the speed of the engrave point's movement. These data is then transfered to the motion control to guide the movement of the engrave point along the z-axis associated with the x-y plane. The results indicate that engraving using this technique is fast and continuous. The specimen obtained looks perfect in 3D view.

As the point sampling technology evolves rapidly, there has been increasing need in generating tool path from dense point set without creating intermediate models such as triangular meshes or surfaces. In this paper, we present a new tool path generation method from point set using Euclidean distance fields based on Algebraic Point Set Surfaces (APSS). Once an Euclidean distance field from the target shape is obtained, it is fairly easy to generate tool paths. In order to compute the distance from a point in the 3D space to the point set, we locally fit an algebraic sphere using moving least square method (MLS) for accurate and simple calculation. This process is repeated until it converges. The main advantages of our approach are : (1) tool paths are computed directly from point set without making triangular mesh or surfaces and their offsets, and (2) we do not have to worry about no local interference at concave region compared to the other methods using triangular mesh or surface model. Experimental results show that our approach can generate accurate enough tool paths from a point set in a robust manner and efficiently.

In this paper, we propose a simple but optimized NC code generating technique for disk cams by means of tool path error control in a five-axis CNC machining center. Using the geometric theorem of the triangle made between manufacturing points and error checkpoint, the tool path error has been studied for disk cams profile generation and an improvement in the profile has been obtained. Then, based on the present manufacturing approach a computer program is developed on $C^{++}$ language to perform and to verify the shape design, the manufacturing simulation, and the optimized generation of the NC code.

This paper proposes a control algorithm, which is verified experimentally, for aspherical surface grinding and polishing. The algorithm provides simultaneous control of the position and interpolation of an aspheric curve. The nonlinear formula for the tool position was derived from the aspheric equation and the shape of the tool. The function was partitioned at specific intervals and the control parameters were calculated at each control section. The position, acceleration, and velocity at each interval were updated during the process. A position error feedback was introduced using a rotary encoder. The feedback algorithm corrected the position error by increasing or decreasing the feed speed. In the experimental verification, a two-axis machine was controlled to track an aspherical surface using the proposed algorithm. The effects of the control and process parameters were monitored. The results demonstrated that the maximum tracking error with tuned parameters was at the submicron level for concave and convex surfaces.

Although conventional contour parallel tool paths obtained from geometric information have successfully been used to produce desired shapes, they seldom consider physical process concerns such as cutting forces and chatter. In this paper, we introduce an optimized contour parallel path that maintains a constant material removal rate at all times. The optimized tool path is based on a conventional contour parallel tool path. Additional tool path segments are appended to the basic path to achieve constant cutting forces and to avoid chatter vibrations over the entire machining area. The algorithm was implemented for two-dimensional contiguous end milling operations with flat end mills, and cutting tests were conducted to verify the performance of the proposed method.

In machining muliple components fixed on the same pallet of a NC machine, it is very important to minimize the total time required to finish the machining by carefully determining the component layout on the pallet, and the tool path of NC machine, and the sequence of tools to be used. In this paper, a linear integer programming model is presented to obtain an efficient layout; and a two-phased heuristic algorithm is proposed to minimize the total time for machining multiple components. Numerical examples are given for the case of identical components and nonidentical components, respectively. The result of either case shows significant reduction of 7.2~15.0% in the total time required to finish the machining.

Knowledge city (KC) enables the knowledge economy (KBE) to foster the generation, circulation and use of knowledge. The KBE leads the industrial innovation through the knowledge based technologies, infrastructure and service, with “making more productive use of inputs, and with “creating new value chain and new production path chains. In a KBE, information communication technology (IT/ICT) plays an important role as a tool of creating, sharing and managing knowledge in KC. Therefore this study seeks to identify the knowledge driven production path through ICT as a tool of knowledge sharing and knowledge management by analyzing the structural impact changes of IT/ICT industries on the other industries in Korea from 2000 to 2010. The data for analysis is the input-output table published by the Bank of Korea in 2000 and 2010. The input-output model and structural path analysis have been used for investigating structural impact changes. As a result, the demand and supply structure of IT/ICT industries were technically changed during 2000 and 2010. First, the production of IT/ICT industries steadily and significantly has increased around 227 percent (176 trillion →399 trillion) between 2000 and 2010. Second, according to input-output coefficient, the demand of IT/ICT industries in 2000 has increased than 2010’s (in agriculture industries: 0.0008, manufacture industries: 0.0005, construction industries: 0.0016, IT/ICT industries: 0.0032, services industries: 0.0041). Third, multiplier analysis showed that IT/ICT industries had a great influence on other industries (in agriculture industries: 0.0472, manufacture industries: 0.3549, construction industries: 0.0155, IT/ICT industries: 0.0156, services industries: 0.1398). While the input-output multiplier of manufacture industries increased the most, but construction increased by the least. Forth, four production paths newly occurred in the backward linkage production path of IT/ICT industries and three production paths were freshly added in the forward linkage production path of IT/ICT industries. The global effect has increased by 0.557 and 0.079 in terms of IT/ICT industries backward and forward linkage production path respectively.

In this study, tool path control algorithm for aspherical surface grinding was derived and discussed. The aspherical surface actually means contact points between lens and tool. Tool positions are generally defined at the center of a tool, so there is difference between tool path and lens surface. The path was obtained from contact angle and relative position from the contact point. The angle could be calculated after differentiating an aspheric equation and complex algebraic operations. The assumption of the control algorithm was that x moves by constant velocity while z velocity varies. X was normal to the radial direction of lens, but z was tangential. The z velocities and accelerations were determined from current error and next position in each step. In the experiment, accuracy of the control algorithm was checked on a micro-precision machine. The result showed that the control error tended to be diminished when the tool diameter increased, and the error was under sub-micro level.

This paper presents an efficient real-time tool-path planning method for interpolation of NURBS surfaces in CNC machining. The proposed tool-path planning method is based on an improved iso-scallop strategy and can provide better precision than the existing methods. The proposed method is designed such that tool-path planning is easily managed in realtime. It proposed a new algorithm, for regulation of a scallop height, which can efficiently generate tool-paths and can save machining time compared with the existing method. Through computer simulations, the performance of the proposed method is analyzed and compared with the existing method in terms of feedrate. total machining time and a degree of constraint on the scallop height.

Recently, according to the various taste of consumers, the design of a product is changed variously and complicatedly. The complicated product is not usually constructed with one patch but multi-patch. By the way, in machining, higher precision and the reduction of leading and machining time is required. But for the multi-patch sculptured surface, the amount of machining data becomes large. This means the increase of leading and machining time. In this study, the tool path generation method with reparameterization is proposed for multi-patch sculptured surface and variable step size using NURBS is used to satisfy the precision and to reduce leading and machining time.

This paper discusses a method to generate the tool path for NC machining of automobile panel dies. The source data representing a panel die may be generated from digitizing machines, other CAD/CAM systems via IGES files, of compound surface models. From the source data, three types of interferencefree tool paths are generated automatically ; a parallel (Cartesian), an isometric, and a pencil cutting tool path. For the interference-free tool path, a polyhedral model composed of several triangles, and an 'offset triangle' approach are exploited. Finally, some practical examples are illustrated.

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.

본 연구에서는 다음과 같은 두가지 관점에서 공구경로 최적화를 위한 기존 방 법의 문제점을 검토하고 이의 개선 방안을 제시하였다. 첫째, 기존의 공구경로 산출 방법에서는 고려되지 않는 공구대의 공구 장착 현황(turret configuration)이 최적화 과정에서 고려되어야 한다. 둘째로, 제작과 관련한 구속조건(manufacturing con- straints)이 최적화 과정에 직접 반영되어야 한다.

Since the punching time is strongly related to the productivity in sheet metal stamping, there have been a lot of efforts to obtain the optimal tool path. However, most of the conventional efforts have the basic limitations to provide the global optimal solution because of the inherent difficulties of the NP hard combinatorial optimization problem. The existing methods search the optimal tool path with limiting tool changes to the minimal number, which proves not to be a global optimal solution. In this work, the turret rotation time is also considered in addition to the bed translation time of the NCT machine, and the total punching time is minimized by the simulated annealing algorithm. Some manufacturing constraints in punching sequences such as punching priority constraint and punching accuracy constraint are incorporated automatically in optimization, while several user-interactions to edit the final tool path are usually required in commercial systems.

Computer numerical control (CNC) part programs generated by computer-aided manufacturing software are frequently composed of numerous G01 blocks. CNC interpolator applies acceleration and deceleration to generate velocity profile of each block. Therefore, the machining time is increased when the number of G01 blocks is increased. To reduce the machining time, corner blending has been used to smooth the corner shape of adjacent blocks. Because the tool path generated by corner bending dose not reach the commanded endpoint, error of the interpolated tool path exists. The objective of this study was to present a method to determine block overlap time to limit tool path error generated by corner blending. An algorithm to calculate tool path error with respect to block overlap time was also proposed. Performance of the proposed algorithm to limit tool path error was demonstrated in this study.

The sheet parts are formed with dies conventionally. But this conventional forming process is not suited to small volume and varied production for the reason of high cost. For the solution of this problem, a new forming process, which is called CNC incremental sheet forming, is being introduced. This process can form sheet parts without die, and is very well suited to small volume and varied production in space flight and automobile. In this paper, dieless CNC forming system based on a machining center is developed. A special device to grasp and pull the blank sheet built in the machining center and tool path generation S/W from STL file of 3-D model are developed. Several sheet parts are incrementally formed to verify the effectiveness of the developed system.