• Title, Summary, Keyword: worm

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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.

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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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.

Development of Durability Estimation and Design Systems of Worm Gears (웜기어의 강도평가 및 설계시스템 개발에 관한 연구)

  • 정태형;백재협
    • 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.

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Application of Piezoceramic Actuator for Inch-Worm (이송 자벌레로의 압전소자 응용)

  • 윤재헌;채재희;김인수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.877-880
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    • 2001
  • This paper presents the new linear motion device so called "inch-worm" which gets large displacement by incrementally summing small displacements of PZT actuators. Dynamics stiffness of inch-worm is generally low compared to its driving condition due to the requirement of inch-worm like small size and light weight. This low stiffness may degenerate the positional precision of inch-worm. An inch-worm is realized using three PZT actuators, a monolithic moving device and a guide way frame. Driving input signal is shaped to reduce the residual vibration of inch-worm by LQG controller and cycloid step input. The practical feasibility of inch-worm is also examined by running test.ning test.

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Application of Piezoceramic Actuator to the Inch-Worm (이송자벌레로의 압전세라믹 작동기 응용)

  • Kim, In-Su;Lee, Hong-Sik;Song, Jun-Yeop
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.8
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    • pp.157-163
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    • 2001
  • This paper presents the new linear notion device so called \"inch-werm\" which gets large displacement by incrementally summing small displacements of PZT actuators. Dynamic stiffness of inch-worm is generally low compared to its driving condition due to the requirement of inch-worm like small size and light weight. This low stiffness may degenerate the positional precision of inch-worm. An inch-worm is realized using three PZT actuators, a monolithic moving device and a guide way frame. Finite element method and experimental approach are used to analyse the static and dynamic motion of the designed inch-worm. Command reference input is shaped to reduce the residual vibration of inch-worm. The practical feasibility of inch-worm is also examined by running tests.ing tests.

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Motion Control of Inch-worm (이송자벌레의 운동제어)

  • Yun, Jae-Heon;Kim, Yeong-Sik;Kim, In-Su
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.9
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    • pp.179-185
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    • 2002
  • Solid state deformation of PZT is effective for the micron scale displacement. Inch-worm gets large linear displacement by incrementally summing displacements of PZT actuators. Dynamic stiffness of inch-worm is generally low compared to its driving condition due to the small size and light weight of inch-worm. Mechanical vibration induced by low stiffness may degenerate the motion accuracy of the inch-worm. In this paper, dynamic characteristics of the inch-worm are modeled by using the frequency domain curve fitting based on the experimental frequency response function. SMC (sliding mode control) is examined for motion control of the inch-worm. Simulation and experimental results show that the inch-worm with SMC scheme is feasible for the precise displacement device.

Quality Evaluation of Low-fat Pork Loaf Containing Silkworm Powder and Vegetable Worm (Paecilomyces japonica) During Cold Storage

  • Jang, Ae-Ra;Jin, Sang-Keun;Jo, Cheo-Run;Lee, Moo-Ha;Kim, Il-Suk
    • Food Science and Biotechnology
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    • v.17 no.4
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    • pp.799-804
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    • 2008
  • This study was performed to determine physicochemical and sensory quality of low-fat pork loaf containing silkworm powder and vegetable worm (Paecilomyces japonica). Total 2% of fat replacer (soy protein isolate:maltodextrin:$\kappa$-carrageenan:water=1:0.5:0.5:10, w/v) was added. The loaf was separated into CTL (control), T1 (0.2% silkworm powder), T2 (0.2% vegetable worm), T3 (0.4% silkworm powder), T4 (0.4% vegetable worm), T5 (0.1% silkworm powder+0.1% vegetable worm), and T6 (0.2% silkworm powder+0.2% vegetable worm). Pork loaf of T3 showed the highest pH value and cooking loss of pork loaves containing silkworm and vegetable worm was higher than control at day 5. 2-Thiobarbituric acid reactive substances of T2 and T5 showed significantly lower values than control and those additives may reduce lipid oxidation of meat. Overall acceptability was not adversely influenced by silkworm powder and vegetable worm at day 0 and 5. These results indicated that those silkworm powder and vegetable worm could be utilized for pork product industry.

Passive Benign Worm Propagation Modeling with Dynamic Quarantine Defense

  • Toutonji, Ossama;Yoo, Seong-Moo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.3 no.1
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    • pp.96-107
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    • 2009
  • Worm attacks can greatly distort network performance, and countering infections can exact a heavy toll on economic and technical resources. Worm modeling helps us to better understand the spread and propagation of worms through a network, and combining effective types of mitigation techniques helps prevent and mitigate the effects of worm attacks. In this paper, we propose a mathematical model which combines both dynamic quarantine and passive benign worms. This Passive Worm Dynamic Quarantine (PWDQ) model departs from previous models in that infected hosts will be recovered either by passive benign worms or quarantine measure. Computer simulation shows that the performance of our proposed model is significantly better than existing models, in terms of decreasing the number of infectious hosts and reducing the worm propagation speed.

A network-attached WORM(Write Once Read Many) storage system (WORM(Write Once Read Many) 지원 네트워크 대용량 저장 장치를 위한 파일 시스템)

  • Kim, Moon-Kyung;Kim, Sun-Tae;No, Jae-Chun;Park, Sung-Sun
    • Proceedings of the IEEK Conference
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    • pp.1177-1178
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    • 2008
  • This paper presents a network-attached WORM(Write Once Read Many) storage system whose purpose is to protect sensitive data that should not be accessed by accidental/intentional intrusion. In our storage system, the sensitive data would be marked and be stored into a specific WORM volume. Furthermore, with the associated WORM mark, the data whose WORM life cycle has been expired would automatically be moved to the general-purpose disk space, without interfering any other tasks, to save the WORM volume space. Our WORM storage system was integrated to the NAS product.

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