• 한국정밀공학회지
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• 제33권11호
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• pp.893-898
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• 2016

Plastic array lens are cheap to manufacture; however, plastic is not resistant to high temperatures and moisture. Optical glass represents a better solution but is a more-expensive alternative. Glass array lens can be produced using lithography or precision-molding techniques. The lithography process is commonly used, for instance, in the semiconductor industry; however, the manufacturing costs are high, the processing time is quite long, and spherical aberration is a problem. To obtain high-order aspherical shapes, mold-core manufacturing is conducted through ultra-precision grinding machining. In this paper, a $4{\times}1$ mold core was manufactured using an ultra-precision machine with a jig for the injection molding of an aspherical array lens. The machined mold core was measured using the Form TalySurf PGI 2+ contact-stylus profilometer. The measurement data of the mold core are suitable for the design criterion of below 0.5 um.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.529-533
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• 1996

Recently, manufacturing industries are doing their best to increase productivity and to reduce production time. One of tile efforts is to develop user-friendly and effective CAM systems. For this purpose, a CAM system for turning was developed. In the developed system. user interacts with tile CAM system using graphical user interface (GUI) and manufacturing support functions to make NC programs effectively. Manufacturing support functions include cycle decoder. interference check be ween tool and workpicce. bar turning without air cut and dynamic/wireframe simulation. In the cycle decoder. basic options are provided to novices for their convenience. and advanced options are provided to help expert to modify the program using their knowledge. Interference check has been nil issue in tile CAM system for tuning. In this paper. when a user selects a tool. interference check between selected tools and workpieces is done automatically. Moreover. remaining shapes are calculated automatically. Then, tile CAM system requests user to input all additional tool and generates NC codes to cut tile remaining shapes. In bar turning of forged raw material, air cut should be prevented for effective machining. For this purpose, a new algorithm for bar turning was developed. Dynamic and wireframe simulation was used to verify the generated NC code.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.35-36
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• 2006

In Nd:YAG laser welding, evaluation methods of welding flaw are various. But, the method due to fume shape is difficult to classification of welding flaw. The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. At the present time, some methods are studied for measurement of fume shape by using high-speed camera and photo diode. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. In this study, fume shape was measured by infrared thermal camera that is non-contact/non-destructive thermal measurement equipment through change of laser generating power, speed, focus. Weld was performed on bead-on method. Measurement results are compared as two equipments. Here, two results are composed of measurement results of fume quantities due to fume shape by infrared thermal camera and inspection results of weld bead include weld flaws by ultrasonic inspector.

• 한국정밀공학회지
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• 제19권9호
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• pp.111-117
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• 2002

In most machining companies, operators decide the cutting condition, a pair of spindle speed (5) and table federate (F) by experience and subjective judgment. As cutting conditions are determined by operators' experience and ability, inconsistent cutting conditions are given in same operating conditions. The objective of this study is to develop the cutting condition decision system which utilizes shop data and predicts tool life by neural network and eventually leads to the optimal cutting condition. The production time per piece is considered for an optimization object. We will discuss the process of an optimal cutting condition decision by neural network. By this process, a series of shop data is stored. And neural network is constructed for prediction of tool life and the optimal cutting condition is recommended from a cutting condition decision system using the stored shop data. The results show that the developed system is rational in searching the optimal cutting conditions on job operations.

• 한국정밀공학회지
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• 제32권2호
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• pp.179-184
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• 2015

In the recent field of Machining, with the improving efficiency of processing, the index table is a key unit according to the increase of parts in available processing when working with the three axes at the same time. As an essential product of MCT, the index tables effect an influence on product quality of machined parts. Therefore, it is necessary to design the shape of index table with stability, high stiffness, lightweight structure. In this study, the optimal shape of index table was proposed using by design of experiment. The maximum displacement and stress analysis were carried out by using FEM software. The optimized shape was verified by using the statistical software. The results of shape optimization were confirmed that both displacement and stress were reduced in comparison with initial model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 춘계학술대회 논문집
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• pp.176-194
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• 1991

A study on the Manufactiring of High-Precision Linear Scale by the Use of He-Ne Laser Interference Of late, along with the advancement of procision machining technology, the reauirement of super-precision measurement increases as time goes on, and the precision and accuracy of standard scale which is a basis of procision measurement has been cognized as a oriterion of industrial development in a nation. Up to now, mechanical and chemical methods have been widely employed to carve scale lines on linear scale, and it is impossible for the linear scale manufactured by means of those methods to guarantee the measurement with sub-micron level owing to errors attended with various problems. And the measuring length also bears errors subjected to the influence of surroundings condition, and shows inefficient circumstances in measurement on the ground of the complexity of measuring procedure as well as massive measuring apparatus. Hence in this paper, we described on technology by which we can carve scale lines thru optical method under the condition of laboratory by using rhcoherence of He-Ne two-mode stabilized laser and in turn, put it to practical use as linear scale for the measurment of lengrh. In this researchin the case of setting scale interval to 20 .mu. m, we employed super-precision scale-carving device associated by Ar larser and acoustic optical modulator in lieu of flsahing lamp scale-carving device, and we consequently obtained superior linear scales carved with precision and accuracy of .+-. 0.3 .mu. m.

• 한국정밀공학회지
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• 제8권3호
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• pp.82-92
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• 1991

A study on the manufacturing of High Precision Linear Scalr using He-Ne Laser interference Of late, along with the advancement of precision machining technology, the requirement of super precision measurement increases as time goes on, and the accuracy of standard scale which is a basis of precision measurement has been cognized as a criterion of industrial development in a nationl. In this paper, we described on technology by which we could carve scale lines thru optical method under the condition of laboratory by using the coherence of He-Ne two-mode stabilized laser and in turn, put it to practical use as linear scale for the measurement of length. Hence in this research in the case of setting scale interval to 20 ${\mu}m$, we employed super precision scale-carving device associated with Ar laser and acousto optic modulator in lieu of flashing lamp scale-carving device, and we obtained as experimental result superior linear scales carved within the accuracy of ${\pm}$0.3${\mu}m$.

• 한국정밀공학회지
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• 제24권4호
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• pp.84-92
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• 2007

Dynamic process planning requires not only more flexible capabilities of a CAPP system but also higher utility of the generated process plans. In order to meet the requirements, this paper develops an algorithm that can select machines for the machining operations by calculating the machine loads. The developed algorithm is based on the multi-objective genetic algorithm that gives rise to a set of optimal solutions (in general, known as the Pareto-optimal solutions). The objective is to satisfy both the minimization number of part movements and the maximization of machine utilization. The algorithm is characterized by a new and efficient method for nondominated sorting through K-means algorithm, which can speed up the running time, as well as a method of two stages for genetic operations, which can maintain a diverse set of solutions. The performance of the algorithm is evaluated by comparing with another multiple objective genetic algorithm, called NSGA-II and branch and bound algorithm.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.149-153
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• 2002

The commutator of an automotive fuel pump motorhas been produced through various processes such as forging, segmenting, and assembling. And the conventional method producing the commutator of an automotive fuel pump motor is not appropriate for saving material and cost, because it makes each segment separated one by one. Therefore a new process design is required in order to avoid the assembling process. In this study, a new process design of the commutator has been carried out to save material and manufacturing time by FE analysis. In the FE analysis, three forging processes are proposed for producing copper(ASTM C11000) commutator of an automotive fuel pump motor. And forging experiments are performed to make an unsegmented commutator in order to verify the theoretically proposed process. And then, in order to get the final product the forged commutator is passed through various postprocessing such as machining, bending, resin forming, and shearing process. From the experimental result the forging process proposed from the FE analysis is verified to be an economical method for producing the commutator for an automotive fuel pump motor.

• 소성∙가공
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• 제22권6호
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• pp.317-322
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• 2013

A radio frequency(R/F) switch connector is widely used in wireless devices such as mobile phone and navigator to check defects of the circuit board of product. The R/F switch connector shell plays a role in protecting the switch connector. Previously, this part was machined using a turning, which is time-consuming and has poor material utilization. Furthermore, the workpiece material of brass containing lead that has excellent machinability has environmentally regulated during recent years. The purpose of the current study was to develop the connector shell by forming through progressive dies including embossing, burring and forging process in order to achieve higher productivity and dimensional accuracy without tool failure. To accomplish this objective, a strip layout was designed and finite element (FE) analysis was performed for each step in the process. Try-out for the connector shell was conducted using progressive die design based on FE-analysis results. Dimensional accuracy of developed part was investigated by scanning electron microscopy. The result of the investigation for the dimensions of the formed connector shell showed that the required dimensional accuracy was satisfied. Moreover, productivity using the progressive die increased four times compared to previous machining process.