• Title, Summary, Keyword: worm gear

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Design of a Reduction Gear using Double-Enveloping Worm Gear (장구형 웜기어를 이용한 감속기 설계)

  • Kim, Tae Woo;Hwang, Young Kug;Lee, Choon Man
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.8
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    • pp.785-789
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    • 2013
  • Worm gear sets may be either single- or double-enveloping. In a single-enveloping set, the worm wheel is cut into a concave surface, thus partially enclosing the worm when meshed. The double-enveloping worm gear is similar to the single-enveloping gear; however, the worm envelopes the worm gear. Thus both are throated. The double-enveloping worm gear has more of the tooth surface in contact than the single-enveloping worm gear. The larger contact area increases the load-carrying capacity. For this reason, double-enveloping worm gearing is widely applied in heavy-duty machinery, for applications including construction and metallurgy. In this paper, we designed a compact reduction gear that is highly efficient using double-enveloping worm gears. We calculated the bearing load in the worm gearing to select the bearing and the housing surface area according to the recommended values from AGMA(American Gear Manufacturers Association). The finite element method was used to assess the structural integrity.

Design and Simulation of Meshing of New Type of Worm-Gear Drive with Localized Contacts

  • Seol, In-Hwan;Chung, Soon-Bae
    • Journal of Mechanical Science and Technology
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    • v.14 no.4
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    • pp.408-417
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    • 2000
  • The design and simulation of meshing of a single enveloping worm-gear drive with modified surfaces is presented. Generally worm-gear is generated by the hob which is identical to the worm. This process guarantees the conjugation between the worm and the gear but results in a line contact at every instant which is very sensitive to misalignment. The localization of bearing contact is necessary to reduce the sensitivity of the worm-gear drive to misalignment. Practically this localization is achieved by application of an oversized worm type hob to cut the worm-gear. The oversized hob approach is very practical and effective to localize bearing contact but can not provide the conjugation between the worm and the modified worm-gear. This work proposes an analytical procedure to make the worm surface conjugate to the worm-gear which is cut by the oversized hob. The developed computer program allows the investigation of the influence of misalignment on the shift of the bearing contact and the determination of the transmission errors, the contact ratio and the principle curvatures. The developed approach has been applied for ZK type of single-enveloping worm-gear drives and the developed theory is illustrated with a numerical example.

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Transmission Error Analysis of ZI and ZA Profile Worm Gears (ZI 및 ZA형 웜기어의 치합전달오차 해석)

  • Lee, Tae-Hoon;Suh, Junho;Park, Noh-Gill
    • 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.

Vibration Characteristics of Worm Gear Faults for Elevators (승강기용 웜기어의 결함에 따른 진동 특성)

  • Lee, S.J.;Yang, B.S.;Lee, S.S.;Park, S.T.;Son, J.D.
    • Journal of the Korea Society For 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.

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Design of Worm Gear for CVVL Paired with ZK Worm and Involute Helical Gear (ZK 웜과 인볼류트 헬리컬기어로 결합된 CVVL용 웜기어 설계)

  • Sohn, Jonghyeon;Park, Nogill;Oh, Chunghan
    • 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.

The Development of Decelerating Motor of Electronic Power Steering (EPS 감속 모터 개발)

  • Lee, Jeong-Ick
    • 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.

Development of Speed Reducer Integrated Driving system Apply to Vehicle Window Motor (차량용 윈도우 모터를 적용한 감속기 일체형 구동부 개발)

  • Youm, Kwang-Wook;Ham, Seong-Hun
    • Journal of the Korea Society For 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.

A Study on the Static/Dynamic Stability and the Fatigue Damages for the Worm Gear in the B-Axis Rotary Table of a Mill Turret (복합공구대용 B축 회전테이블 웜 기어의 정/동적 안정성 및 피로에 관한 연구)

  • Kim, Chae-Sil;Kang, Seung-Hee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.5
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    • pp.107-115
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    • 2014
  • Highly functional mill turrets have been developed and continuously improved to shorten the manufacturing time and enable multiple uses. Among these, a mill turret with B-axis rotary table was developed. The B-axis rotary table should be evaluated for structural integrity. Moreover, its worm and worm gear for transmitting power should be able to endure fatigue damage. Therefore, this article presents a structural analysis of this type of B-axis rotary table and confirms its static stability by comparing the stress results to the allowable stress levels. Next, the dynamic stability of the rotary table was investigated via a mode analysis and a harmonic analysis in a range determined by the results of a modal analysis. Finally, a worm gear set, the main part that drives the rotary table, is analyzed for fatigue and to estimate its lifetime. The results of the fatigue analysis allowed a prediction of the life of the worm gear set. The analytical results show that the B-axis rotary table has good structural integrity.

Tooth Durability Evaluation of n Cylindrical Worm Gear by Contact Line Analysis (원통형 웜기어의 접촉선 해석)

  • Cheon, Gill-Jeong;Han, Dong-Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.7
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    • pp.1231-1237
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    • 1999
  • Applying the conjugate contact condition, contact lines of a cylindrical worm gear has been calculated. The characteristics of tooth contact were analyzed and the pitting resistance were also assessed. It has been verified that: i) the length of contact is shortest on the 1st tooth of the front region, ii) the contact region is more narrow in the recess side than in the access side, iii) the contact region is more narrow in worm than in worm wheel. Hence, the pitting resistance is weakest in the recess side of the 1st contacting worm tooth.