• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.265-270
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• 1997

Helical gear system is utilized to transmit motion between parallel shafts. The axial thrust loads on the shafts are existed. On each of the support shafts, at least one of the bearings should be able to support the axial loads. The reliability and life analysis are based on the two-parameter Weibull distribution lives of the component gears and bearings. The computer calculates the system lives and dynamic capacities of the components and their system. The system life is defined as the life of the component or the helical gear system at an output torque at which the probability of survival is ninety percent.

• 한국분말재료학회지
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• 제19권3호
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• pp.189-195
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• 2012

A novel PM (powder metallurgy) steel for automotive power-train gear components was developed to reduce manufacturing cost, while meeting application requirements. The high-density PM steel was manufactured by mixing using special Cr-Mo atomized iron powders, high-pressure compaction, and sintering. Tensile strength, charpy impact, bending fatigue, and contact fatigue tests for the PM steel were carried out and compared to conventional forged steel. Pinion gears for auto-transmission were also manufactured by helical pressing, sintering, and surface densification process. In order to evaluate the durability of the PM parts, auto-transmission durability tests were performed using dynamometer tests. Results showed that the PM steel fulfilled the requirements for pinion gears indicating suitable tensile, bending fatigue, contact fatigue strengths and improved gear tooth profile. The PM gears also showed good performance during the transmission durability tests. As a result, the PM gears showed significant potential to replace the conventional forged steel gears manufactured by tooth machining (hobbing, shaving, and grinding) processes.

• Tribology and Lubricants
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• 제34권6호
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• pp.325-331
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• 2018

Automobiles and systems requiring high gear ratios and high power densities generally use worm gears. In particular, as worm gears have a small volume and self-locking function, home appliances such as refrigerators and washers consist of worm gears. We can classify worm gears into cylindrical worms and rectangular worms. According to the AGMA standard, there are four types of cylindrical worms, ZA, ZN, ZK and ZI, depending on the machining of the worm shaft. It is preferable to use a ZI-type worm shaft, which is a combination of a worm wheel having an involute helical tooth surface and a conjugate tooth surface. However, in many cases, industries mostly use ZK, ZN, and ZA worm shafts because of the ease of processing. This paper presents numerical approaches to produce ZI and ZA worm surfaces and worm wheel. For the analysis of the transmission error of a worm gear system, this study (1) generates surface profile functions of ZI profile worm gear and worm shaft based on the common rack theory, (2) adopts the Newton-Raphson method for the analysis of the gear surface contact condition, and (3) presents and compares the corresponding transmission errors of ZI and ZA worm gears.

• 한국기계가공학회지
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• 제10권2호
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• pp.32-37
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• 2011

This study developed Gear Automatic Design Program that users with the basic knowledge about mechanical engineering can easily model spur gears and helical gears. The Gear Automatic Design Program used Visual LISP which is an user program based on Auto CAD and made it model the gears with involute tooth by the exact mathematic definition. Also, to verify these, the reliability was secured by comparing it with a gear generated in commercial software. And we will develop nitrocarburising process and solve problems which had been caused of SCM440's dimensional changing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.199-203
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• 2004

In this paper, a simplified model is studied to predict analytically the radiated noise from the helical gear system due to an axial excitation of helical gear. The simplified model describes gear, shaft, bearing, and housing. To obtain the axial force of helical gear, mesh stiffness is calculated in the load deflection relation. The axial force is obtained from the solution of the equation of motion, using the mesh stiffness. It is used as a longitudinal excitation of the shaft, which in turn drives the gear housing through the bearing. In this study, the shaft is modeled as a rod, while the bearing is modeled as a parallel spring and damper only supporting longitudinal forces. The gear housing is modeled as a clamped circular plate with viscous damping. For the modeling of this system, transfer function from the shaft to the clamped plate are used, using a spectral method with four pole parameters. Out-of-plane displacement for the thin circular plate with viscous damping is derived and sound pressure radiated from the plate is also derived. Using the model, parameter studies are carried out.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.661-666
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• 2004

The purpose of this study is to measure the rotational vibration, radial vibration, and axial vibration for the helical gear with the wide face width relative to the whole depth. For this purpose, the experimental apparatus is designed and manufactured. The gear vibration of each direction is measured by the accelerometers attached at the gear body. As a result, meshing frequency and second harmonic component are greatly contributed to the gear vibration. As the rotational speed is increased, meshing frequency component has the more significant peak than the second harmonic one. However, the doubled torque decreases the vibration magnitude on the contrary and changes order of the vibration magnitude in each direction.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 제2회 단조심포지엄 단조기술의 진보
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• pp.180-187
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• 1995

Helical gears are machined from blanks, which are usually prepared by forging cylindrical billets at high temperatures through buster, blocker and finisher processes. As dimensions of the blank are closer to those of the machined part, machining cost can be more reduced. Therefore, there are a lot of efforts being made to optimize the forging processes in order to produce near-net shaped blanks. In the present investigation, a rigid viscoplastic finite element technique was used to analyze a helical gear blank hot forging processes and deformation, strain and temperature distributions, forging load variations during forging were obtained. In the paper, it is discussed how these results can be utilized to optimize die design, billet dimensions and press usage.

• 한국정밀공학회지
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• 제13권5호
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• pp.95-103
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• 1996

This paper describes a computer aided design system for spur and helical gears. To establish the appropriate program, an integrate approach based on a rule-base system was adopted. This system is implemented on the personal computer and its environment is a commercial CAD package called AutoCAD. This system includes a main program and five sub-modules such as data input module, tooth profile drawing module, strength calculation module, and drawing edit module. In the main program, all the sub-modules are loaded and the type of gear and tooth profile are selected. In the data input module, the variables which are necessary to the design of gear are selected from the database. In the drawing module, from the calculated results, the required gear tooth is produced on the screen. The developed system that aids gear designer provides powerful capabilities for gear design.

• 한국기계가공학회지
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• 제20권3호
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• pp.92-99
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• 2021

An automatic transmission, which consists of several decks of planetary gear sets, provides multiple speed and torque ratios by actuating brakes and clutches (mechanical friction components) for connecting central members of the planetary gear sets. The gear set consists of the sun gear, the ring gear, and the carrier supporting multiple planet gears with pin shafts. In designing a new automatic transmission, there are many steps to design and analyze: gears, brakes and clutches, shafts, and other mechanical components. Among them, selecting thrust bearings that not only allow the relative rotation of the central members and other mechanical components but also support axial forces coming from them is important; doing so yields superior driving performance and better fuel efficiency. In selecting thrust bearings, the magnitude of axial forces on them is a critical factor that affects their bearing size and performance; its results are systematically related to the direction of the helical angle of each planetary gear set (a geometric design profile). This research presents the effects of the helical angle direction on the axial forces acting on thrust bearings in an automatic transmission consisting of planetary gear sets. A model transmission was built by analyzing kinematics and power flows and by designing planetary gear sets. The results of the axial forces on thrust bearings were analyzed for all combinations of helix angle directions of the planetary gear sets.

• 한국기계가공학회지
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• 제19권10호
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• pp.36-43
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• 2020

A marine turning gear is the main auxiliary machine that enables the disassembly of and maintenance on the main engines. In this study, a marine turning gear based on a helical planetary reducer was developed through analysis of a marine turning gear based on a spur planetary reducer. Nonlinear numerical analysis was performed to determine the ideal contact ratio between the sun gear and the idle gear. Based on this, the surface durability, tooth bending strength, and contact ratio were calculated. In addition, the helix direction was selected to utilize the existing bearings. Gears were manufactured based on the helical gear design values, and the turning gear was evaluated using the FTA standards of MAN Co. Ltd. As a result, a lifetime of 3,000 to 5,000 hours was verified, the maximum torque measured was 105kNm, and the efficiency was measured to be 87.4%.