• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.22-25
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• 2009

Development of a curvic-coupling was presented in this paper. The research covers design, structural analysis, hot-temperature-torsion-test, curvic-coupling applied proto-type turbine disk manufacturing, and assembly test of a curvic-coupling rotor system for the turbopump application. Curvic-coupling was designed based on the Gleason-standard-tooth shape. The load capability of the designed curvic coupling was validated by the structural analysis and hot-temperature-torsion-test. A proto-type turbine disk which had adopted designed curvic-coupling was manufactured, assembled and tested to reveal that shaft-disk assembly run-outs in axial and radial directions were much smaller than the design requirements. The development will be finalized after spin test of shaft-disk assembly in near future.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.28-33
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• 2008

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.1
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• pp.110-116
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• 2013

Curvic coupling of mill turret should maintain disk weight and the cutting resistance which occurs the machining operation and must also have power transmission function. In order to improve machining operation range, the ejecting distance from curvic coupling to the disk must increase as much as possible. But moment is increased by the lack of capacity of the curvic coupling. Increase of moment is the cause of vibration/noise and degradation of machining performance not only stability problem. The manufacturer of mill turret has no the design information between the ejecting distance and the cutting resistance with safety of curvic coupling. Therefore this study describes a finite element analysis model of mill turret using ANSYS workbench. The structural analyses and modal analyses with varying of the ejecting distances and cutting resistances are performed. Finally the equation for relationship between the critical ejecting distance and the cutting resistance is defined under 5 of the safety factor for the maximum von-Mises stress at the curvic coupling.

• Tribology and Lubricants
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• v.34 no.1
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• pp.23-32
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• 2018

Coupling is a mechanical component that transmits rotational force by connecting two shafts. Curvic coupling is widely used in high-performance systems because of its excellent power transmission efficiency and easy machining. However, coupling applications change dynamic behavior by reducing the stiffness of an entire system. Contact surface stiffness is an important parameter that determines the dynamic behavior of a system. In addition, the roughness profile of a contact surface is the most important parameter for obtaining contact stiffness. In this study, we theoretically establish the process of contact and bending stiffness analysis by considering the rough surface contact at Curvic coupling. Surface roughness parameters are obtained from Nayak's random process, and the normal contact stiffness of a contact surface is calculated using the Greenwood and Williamson model in the elastic region and the Jackson and Green model in the elastic-plastic region. The shape of the Curvic coupling contact surface is obtained by modeling a machined shape through an actual machining tool. Based on this modeling, we find the maximum number of gear teeth that can be machined according to the contact angle. Curvic coupling stiffness is calculated by considering the contact angle, and the calculation process is divided into stick and slip conditions. Based on this process, we investigate the stiffness characteristics according to the contact angle.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.87-92
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• 2018

As gas turbines for power generation become increasingly more important for high capacity and high efficiency, the technological development and investment of companies are increasing globally. Gas turbine manufacturing technology is only owned by a few companies such as GE, Siemens, and MHI, and our country currently depends on imports of processing technology and component parts. The core part of the gas turbine is curvic coupling tooth processing technology that improves turbine efficiency by smoothly transmitting power to the turbine rotor. Curvic coupling tooth machining and evaluation research is restricted overseas, and it is not underway in Korea. Therefore, in this study, roughing and finishing process technology for curvic coupling tooth machining is developed and a quantitative evaluation method is proposed. For the development of machining technology, the analysis of critical parameters was performed through C & E analysis. In the roughing process, the conditions considering the minimum machining time and tool load ratio were determined. Finishing process conditions were determined based on the contact ratio between the tooth surfaces. The image-processing method is presented for evaluation of the contact ratio and a verification test was performed.

• Tribology and Lubricants
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• v.40 no.1
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• pp.8-16
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• 2024

This study conducts numerical modeling and eigen-analysis of a rod-fastened rotor, which is mainly used in aircraft gas turbine engines in which multiple disks are in contact through curvic coupling. Nayak's theory is adopted to calculate surface parameters measured from the tooth profile of the curvic coupling gear. Surface parameters are important design parameters for predicting the stiffness between contact surfaces. Based on the calculated surface parameters, elastoplastic contact analysis is performed according to the interference between two surfaces based on the Greenwood-Williamson model. The equivalent bending stiffness is predicted based on the shape and elastoplastic contact stiffness of the curvic coupling. An equation of motion of the rod-fastened rotor, including the bending stiffness of the curvic coupling, is developed. Methods for applying the bending stiffness of a curvic coupling to the equation of motion and for modeling the equation of motion of a rotor that includes both inner and outer rotors are introduced. Rotordynamic analysis is performed through one-dimensional finite element analysis, and each element is modeled based on Timoshenko beam theory. Changes in bending stiffness and the resultant critical speed change in accordance with the rod fastening force are predicted, and the corresponding mode shapes are analyzed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.823-824
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• 2008

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.1
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• pp.100-107
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• 2020

As demand for high value-added products with hard materials increases, the line center is used for producing high value-added products in many industries such as aerospace, automobile fields. The line center is a key device for smart factory automation that can improve the production efficiency and the productivity. Therefore, the development of a mill-turn line center is necessary to produce high value-added products with complex shapes flexibly. In the mill-turn process, a milling process and a turning process are combined. In particular, the turning process needs to increase the rigidity of the spindle. The purpose of this study is to analyze the thermal-structural stability through thermo-structural coupled analysis for a mill-turn spindle with a curvic coupling. The maximum temperature and thermal stability of the spindle were analyzed by thermal distribution. In addition, the thermal deformation and thermal-structural stability of the spindle were analyzed through thermo-structural coupled analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.7-11
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• 2011

A velocity-compounded(VC) turbine for the 75ton turbopump was developed as an improved performance backup for the single-rotor baseline turbine. Curvic coupling was adopted for the power transmission between the rotors and shaft. High temperature torsion test and spin test was performed for the curvic coupling design validation. Aerodynamic performance test revealed that VC turbine can generate 20.5% higher specific power than the baseline turbine.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.3
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• pp.40-46
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• 2011

A velocity-compounded(VC) turbine of the 75ton turbopump was developed as an improved performance backup for a single-rotor base-line turbine. Curvic coupling was used for the connection between rotors and shaft. High temperature torsion test and spin test was performed for the curvic coupling design validation. Aerodynamic performance test revealed that the developed VC turbine can generate 20.5% higher specific power than the base-line turbine. It has been measured that $1^{st}$ rotor of the subject turbine generates 74.1% of total power at design operating condition.