• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.1-9
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• 2020

Using kerosene and liquid oxygen, 1.5-tonf class liquid-liquid pintle injector with rectangular two-row orifice was designed and manufactured. The combustion test of the pintle injector was carried out to verify the combustion performance and combustion stability under a supercritical condition which is the actual operation condition of the liquid rocket engine. The combustion test result showed that the pintle tip was damaged by the high temperature combustion gas in the high-mixed ratio recirculation zone of the combustion chamber. To solve this problem, the insert nozzle was installed in the pintle injector to increase cooling performance at the pintle tip. As a result of the hot firing test, installation of the insert nozzle, AR and BF had a great effect on pintle tip cooling performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2430-2435
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• 2015

In order to achieve high flexibility in manufacture, analysis of chip's shape is one of the most important problems. This paper describes the change of machining characteristics in workpiece materials depending on turning clearance angle. The experiments start from choosing three workpiece materials that are SM45C(machine structural carbon steel), STS303(stainless steel), SCM415 (chrome-molybdenum steel). Then, the experiments show specifically how features of selected materials changed when they were processed with diverse machining depths and with feed rate starting from fixed rotational speed. Especially, the experiments were also analyzed in chip's shape and wear of insert tip. In conclusion, these experiments show that chip's shape was changed by quality of the materials, depth of cut, and conveying speed. When machining feedrate and machining depth were 0.10mm/rev and 0.3mm respectively, workpiece materials showed the best shapes, not categorizing quality of the materials and machining characteristics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.10-16
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• 2021

Drilling is a crucial process that takes up a significant amount of weight during machining operations. In addition, drill tip-type tools and related operations have been developed for manufacturing industries to achieve economic efficiency. In this study, SM45C carbon steel, widely used for machine structures, was utilized as the working material after quenching and tempering. Insert-tip types of carbide tools, such as TiN and TiAlN, were used as tool materials. Drilling conditions such as the spindle revolution, feed rate, step of cut, and tool diameter were used to measure roughness, roundness, and straightness using the orthogonal array table statistical method. The surface roughness, roundness, and straightness characteristics based on the conditions were analyzed using ANOVA. The results showed that the spindle speed and feed rate were the main factors influencing carbide insert-tip drilling under the same conditions as the experimental conditions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.399-406
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• 2001

This study describes the geometric characteristic and the 5-axis machining method of end mill body with insert tip. The geometry of end mill body is consisted of the flute part and the insert tip part. Thus, this study defines the flute part as ruled surface with constant helix angle and the insert tip part as rectangular plane on general direction. The geometric algorithm and the 5-axis NC part program were calculated by our programmed software and a sampled end mill body was machined on 5-axis machining center equipped with two index tables. The machined end mill body with insert tip was very agreeable to the designed end mill body with insert tip. Thus, the method proposed in this study may be very useful for the machining of end mill body with insert tip.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.388-392
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• 2003

As the machine tool industry progresses, the performance of cutting tools also needs to be of good quality and specialized. If the existing metal cutting tool tip is coated properly, its life would be longer and the machining of a difficult-to-cut material also could be possible. For the development of the high quality cutting tool, the applicabilities of TiAIN coating deposited by PVD on the cutting insert were experimentally investigated. The various measurements, such as, SEM micrograph, XRD pattern, AFM surface morphology, and hardness were performed to cross-check the possibility and availability of TiAIN coated tool in the field. The effects of it is successful and we hope to see good results in many fields.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.6
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• pp.1-9
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• 2002

This study describes the geometric characteristics and the 5-axis machining method in order to make end mill cutter coming with insert tips. End mill geometry is consisted of flute part and insert tip part. Flute part modeled by using ruled surfaces with constant helix angle, and insert tip part modeled by rectangular planes containing tapped hole of specified direction in its center. In this study, the modeled insert tip part considered both of a radial rake angle and a axial rake angle, because they were important cutting conditions. In order to machining the virtual end mill defined from geometric characteristics, we programmed a special software to machining the end mill considered in this study. This software can generate NC-codes about following processes, end milling or ball end milling of flute part end milling of rectangular plane, centering of hole, drilling of hole, and tapping of hole. Ant sampled end mills were modeled and machined on 5-axis CNC machining center with two index tables. Since machined end mills were very agreeable to designed end mills, we saw that the method proposed in this study can be very useful for manufacturing of end mill body with insert tip.