• Tribology and Lubricants
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• v.34 no.6
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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.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.65-71
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• 2007

According to the survey, abnormal condition of the system is the main source for interrupting an elevator service, especially faults in worm gears used for the traction machine. Worm gear is popularly used in traction machine for middle and low speed elevators. Elevators need high reliability and stability, because they are closely related to human life. Usually, traction machine is applied to drive the elevators that have height about 35 m and it is an important mechanical unit for riding quality in elevators. There are some research results about types of vibration fault for worm gear in International Association Elevator Engineers (IAEE). But this study concerns with diagnosis of various faults in elevator worm gear using vibration signal. The analysis of fault characteristics is compared with previous researches in traction machine.

• Journal of Power System Engineering
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• v.20 no.1
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• pp.57-62
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• 2016

In this study, design the core part of the driving of the robot. The power of the driving is window motor for automobiles obtained by using a method of directly to the motor shaft of the worm gear type. The decelerator consists of a worm gear to receive power from the motor shaft, Helical gear contact to worm gear, a pinion gear to be connected in line with the helical gear, and an output shaft to be engaged to the pinion gear. Drive system by using the power from the motor shaft based on the deceleration gear designed by the gear ratio set by the gear teeth increases the torque.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.77-84
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• 2014

The worm gear is used in the motor drive system of automotive CVVL because of its compactness and self-locking ability. A ZK worm and an involute helical gear can be meshed in order to reduce production cost. However, the gearing is not suitable for the reliability and the NVH problem. To improve the dynamic performances, an optimal design process is considered. The transmission error is calculated theoretically and minimized with the several gear design parameters. An inequality condition such as the teeth interference elimination is added.

• Journal of the Korea Convergence Society
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• v.2 no.2
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• pp.27-34
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• 2011

This study is making a product for the development of one process worm wheel of making a shape for gear for worm wheel without hobbing manufacturing process. Because of removing a hobbing process, plastic worm wheel for increased productivity and equivalent quality is produced in the result. As the result, this product is selling to Hyundai Mobis, Mando, TRW, KOYO/NSK/Showa(Japan), Delphai(America). The core technology and different strategy are as follows. The technology protection for molding of worm whee is currently patent process "Molding process of helical gear(No. 10-2008-0105908). Further patent procedure for "molding system for positioning decision of inserting boss is currently prepared. As gear molding procedure in hobbing machine without gear machining procedure, most of all, core development technology which is making a gear tooth is main topic. So that, in case of currently developed worm wheel, because core and mold base are not developed in the first procedure, gear is machining in hobbing M/C as the second procedure. In the later, patent for mold base structure will be prepared in this study results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.1-7
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• 2018

We aimed to develop a high quality 3.5 ton class swing reducer by studying the efficiency improvement of the reducer through the optimum design and performance evaluation of the assembled, high efficiency, lightweight 3.5 ton swing reducer. Based on the optimal design of the worm and worm wheel, the optimal manufacturing method of the worm wheel, the optimized casing design, and the optimum design of the output pinion, Respectively. Therefore, in this paper, to improve the efficiency of the worm gear reducer system, we will develop the manufacturing technology and verify the mass production by combining the manufacturing process design, processing and assembling technology according to the optimization design. We have conducted research to realize mass production by product verification such as product efficiency, reliability and durability according to optimal design of worm gear reducer.

• Journal of Biosystems Engineering
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• v.22 no.4
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• pp.497-502
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• 1997

Automation facilities of greenhouses have been continuously developed. However, the conventional two-stage worm gear reducer reveals some problems, including low transmission efficiency. The worm gear reducer also have some difficulties in manufacturing and short life. Therefore, this study was performed to develop a planetary gear reducer, having a high Sear reduction ratio and high torque transmission efficiency. The planetary gear system consisted of a fixed ring gear and a 2-teeth differential ring gear turning slow, as the planetary pinion orbits fast around the fixed ring gear. The developed gear system can achieve a high speed reduction rate at one stage. The reducing system was employed to the greenhouse ventilation system. The reducer has the transmission efficiency of 70.5%, 2∼3 times longer life time, and twofold roll-up torque at an affordable price, comparing with conventional reducers. This reducer can be also applied to many industrial equipments, such as industrial crane, hoist, elevator and gondola etc.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.137-141
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• 2011

Driving mechanism, the central part of a robot, was designed in this study. Power for the motive drive was acquired by directly connecting the motor shaft in worm shape of the low-end DC motor, car window motor, to a decelerator. The decelerator consists of a worm gear to receive power from the motor shaft, a pinion gear to be connected in line with the worm gear, and an output shaft to be engaged to the pinion gear. Motion driving is achieved by the power from the motor shaft with the designed gears, transferred to the deceleration mechanism and to the output gear.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.589-596
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• 2021

In this study, the optimum gating system was designed, and the two zinc alloy worm gears were manufactured in single process by applying a symmetrical gating system with 2 runners. The SRG ratio is set to 1 : 0.9 : 0.6, and the cross-sectional shapes such as sprue, runner and gate are designed. In order to determine whether the design of the gating system is appropriate, casting analysis was carried out. It takes 4.380 s to charge the casting 100%, 0.55 to 0.6 m/s at the gates and solidification begins after the casting is fully charged. The amount of air entrapment is 2% in the left gear and 6% in the right gear. Hot spots occurred in the center hole of the gear, and pores were found to occur around the upper part of the hole. Therefore, the design of the casting method is suitable for worm gears. CT analysis showed that all parts of worm gear were distributed with fine pores and some coarse pores were distributed around the central hole of worm gear. The yield strength and tensile strength were 220 MPa, 285 MPa, and the elongation rate was 8%. Vickers hardness is 82 HV.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.207-216
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• 1997

We developed the durability estimation and design systems to minimize the volume, considering the durability, efficiency, and design requirements of worm gears. That is, we consider each kind of factors affecting on durability on the basis of AGMA Standard for the cylindrical and double-enveloping worm gears. We also estimate input power on the basis of wear and durability, bending strength and deflection of worm shaft, and we developed the durability estimation and design systems of power transmission worm gears introducing the optimal design method on the personal computer to be easily used in field. Also, we developed a method which converts the design variables obtained from the optimal design method to integer values(number of worm threads, number of worm threads, number of worm wheel teeth, etc.,) to be used in real design and production. The developed durability estimation and design method can be easily applied to the design of worm gears used as power transmission devices in machineries and is expected to be used for weight minimization of worm gear unit.