• Title/Summary/Keyword: Bearing

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Design of a Wheel Bearing Unit Using Taguchi Method (다구찌 방법을 이용한 휠 베어링 유니트의 형상설계)

  • 안태길;이상훈
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.10
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    • pp.164-168
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    • 2003
  • An automotive wheel bearing is one of the most important components to guarantee the service life of a passenger car. The endurance life of a bearing is affected by many parameters such as material properties, heat treatment, lubrication conditions, operating temperature, loading conditions, bearing geometry, the internal clearance of bearing and so on. In this paper, we analyze the relation between loads and deformations of wheel bearing units for optimal bearing unit design. On the basis of it, we calculate the endurance life of w heel bearing units and analyze the contribution of bearing geometric parameters on the endurance life by using Taguchi method.

FE Lubrication Analysis and Dynamic Characteristics of Herringbone Groove Air Bearing applied to High-Speed Color Wheel

  • Lee, An-Sung
    • KSTLE International Journal
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    • v.9 no.1_2
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    • pp.1-6
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    • 2008
  • In this study is performed a complex lubrication analysis of a herringbone groove air journal bearing, which shows a big potential as an oilless bearing for a color wheel used as an original color source for a large DLP projection television and rotating at a rated-speed of 10,800 rpm. The Galerkin FE and perturbation methods are used for a lubrication analysis of the bearing. The effects of groove number, angle and depth and bearing clearance on the dynamic stability of the bearing are investigated in terms of the critical mass, and its equilibrium positions, stiffness and damping coefficients are calculated at various rotating speeds. Results have shown that the designed herringbone groove air journal bearing is quite suitable as a support bearing for the considered high-speed color wheel in terms of the complex lubrication performances of the bearing itself.

Analysis and Control of a 3-Phase VR Type Self-Bearing Step Motor for Small Angle Control Considered the fringing Effect (프린징효과를 고려한 미세각도 제어용 3상 가변형 셀프베어링 스텝모터의 해석 및 제어)

  • Kim, Daegon
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.10
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    • pp.93-100
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    • 2001
  • The analysis and control of a new type unsymmetrical slotted self-bearing step motor for small angle control is presented. The motor actuator is used for both motor and bearing functionality without any additional coil windings or electromagnets for bearing functionality. A circular-arc, straight-line permeance model for the fringing effect is presented. An unsymmetrical slotted self-bearing step motor layout and control algorithm are described. A new control current generation method using the electromagnets layout geometry, which needs no additional current for bearing functionality, is proposed. As the result of this analysis the fringing effect largely influences on the system characteristics. especially in torque. Even if the bearing functionality is added into the motor functionality, it is shown that the magnitude of torque is not changed.

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Development of a HDD Spindle Motor Using Passive Magnet Bearing and Fluid Dynamic Journal Bearing (수동형 자기 베어링과 유체 동압 저널베어링을 이용한 HDD용 스핀들 모터 개발)

  • Lee, Chung-Ill;Kim, Hak-Woon;Jang, Gun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.473-477
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    • 2005
  • This paper presents a highly efficient HDD (Hard Disk Drive) spindle motor with a passive magnetic thrust bearing and a fluid dynamic journal bearing and its effectiveness is verified through experiment. It eliminates the mechanical friction loss of a thrust bearing which is around 18% of total power consumption of a 3.5' HDD spindle motor, by replacing a conventional fluid dynamic thrust bearing with a passive magnetic thrust bearing. The passive magnetic thrust bearing using permanent magnets is inherently unstable in radial direction. However, the radial fluid dynamic force of the fluid dynamic journal bearing counterbalances the radial magnetic force of magnetic thrust bearing to achieve the stability as the motor spins up. It has less or equivalent runout and less flying height than the conventional spindle motor.

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A Study on Dynamic Characteristics of a Rotor-Bearing System Supported by Actively Controlled Fluid Film Journal Bearing (능동 제어 유체 윤활 베어링으로 지지된 축-베어링 시스템의 동특성에 관한 연구)

  • No, Byeong-Hu;Kim, Gyeong-Ung
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.8
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    • pp.116-121
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    • 2001
  • The paper presents the dynamic characteristics of a rotor-bearing system supported by an actively controlled hydrodynamic journal bearing. The proportional. derivative and integral controls are adopted for the control algorithm to control the hydrodynamic journal bearing with an axial groove. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than conventional analysis, which uses the Reynolds condition. The speed at onset of instability of a rotor-bearing system is increased by both proportional and derivative control of the bearing. The proportional control increases the stability threshold without affecting the whirl ratio. However, for the derivative control of the bearing, increase of stability threshold speed is accompanied by a parallel reduction of the whirl ratio. The integral control has no effect on stability characteristics of hydrodynamic journal bearing. The PD-control is more effective than proportional or derivative control. Results 7how the active control of bearing can be adopted for the stability improvement of a rotor-bearing system.

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A Comparative Study on Bearing Capacity of Single Pile Based on Calculation Method (산정방법에 따른 단말뚝의 지지력 비교연구)

  • 이영대;심재현
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.39 no.2
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    • pp.124-133
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    • 1997
  • Pile load test is good for estimating pile bearing capacity, but using this method is limited by time and cost required. Dynamic and static method is more convenient and economical, but confidence of estimated value by dynamic and static method are lower than that of pile load test. After being compared pile bearing capacity data obtained from pile load test with those of other two methods, the results from this study were summarised as follows. For allowable bearing capacity values greater than 175t per pile, bearing capacity acquired from static method was higher than that acquired from pile load test, whereas bearing capacity acquired from pile load test was higher than that acquired from static method for values under 175 per pile. It was that variance of bearing capacity was large when bearing capacity obtained by dynamic method was higher than 250t. Also bearing capacity based on dynamic method was higher than that based on pile load test. Allowable bearing capacity get from dynamic method suggested that carefull precautions are necessary in application for allowable bearing capacity values higher than 2S0ton per pile.

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A Combined Bearing Arrangement for High Damping Spindle Systems (고감쇠 주축 시스템을 위한 베어링의 복합배열에 관한 연구)

  • Lee, C.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.10
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    • pp.139-145
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    • 1996
  • The machining accuracy and performance is largely influenced by the static, dynamic and thermal characteristics of spindle systems in machine tools, because the spindle system is a intermedium for cutting force from tool and machine powef from motor. Large cutting force and power are transmitted by bearing with a point or line contact. So, the spindle system is the static and dynamic weakest point in machine structure. For improvement of static stiffness of spindle system can be changed design parameters, such as diameter of spindle, stiffness of bearing and bearing span. But for dynamic stiffness, the change of the design parameters are not useful. In this paper, the combined bearing arrangement is suggested for high damping spindle system. The combined bearing arrangement is composed of tandem double back to back arrangement type ball bearins and a high damping hydrostatic bearing. The variation of static deflection and amplitude in first natural frequency is evaluated with the location of hydrostatic bearing between front and rear ball bearing. The optimized location of hydrostatic bearing for high static and dynamic stiffness is determined rapidly and exactly using the mode shape and transfer function of spindle. The calculation of damping effect on vibration by unbalance of grinding wheel and pulley in optimized spindle system is carried out to verify the validity of the combined bearing arrangement. Finally, the simulation of grinding process show that the surface roughness of workpiece with high damping spindle system is 60% better than with ball bearing spindle system.

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A study on the design, manufacturing and performance evaluation of air bearing spindle for PCB drilling (PCB드릴링용 공기 베어링 스핀들의 설계 제작 및 성능평가에 관한 연구)

  • Kim Sang-Jin;Bae Myung-Il;Kim Hyeung-Chul;Kim Ki-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.4 s.181
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    • pp.29-36
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    • 2006
  • Micro drilling by high-speed air bearing spindle is very useful manufacturing technology in electronic industry For the design of high speed air bearing spindle, there are considered stability of air bearing spindle, allowable load of air bearing, run out and tooling system design for micro drill's attach and remove. According to suggested details, we designed and manufactured high-speed air bearing spindle and carried out performance estimation such as run out, temperature change in running air bearing spindle, stiffness, chucking torque. Results are follows; Run out was measured under $5{\mu}m$ at air bearing spindle revolution $20,000\sim125,000rpm$. High speed air bearing spindle's temperature rose about $20^{\circ}C$ after 5 minutes from running and then was fixed. Allowable thrust load of spindle was 17kgf. Chucking torque of collet was 15kgfcm.

Bearing Strength of Glass Fiber Reinforced Glulam Bolted Connection

  • Kim, Keon-ho;Hong, Soon-il
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.5
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    • pp.652-660
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    • 2015
  • To study the bearing characteristics of glass fiber reinforced glulam for structural design, bearing strength tests were performed. Bearing loads were applied in the direction parallel to the grains, and the holes were prepared in such a way that the bolts would bear and support all the layers. The yield bearing strengths of the glass fiber reinforced glulam were found to be similar to those of the non-reinforced glulam, and were almost constant regardless of increases in bolt diameter. The ratio of the experimental yield bearing strength to the estimated bearing strength according to the suggested equation of the Korea Building Code and National Design Specification was 0.91~1.03. For the non-reinforced glulam and the sheet glass fiber reinforced plastic glulam, the maximum bearing load was measured according to the splitting fracture of specimens under bolt. The textile glass fiber reinforced glulam underwent only an embedding failure caused by the bearing load. The failure mode of reinforced glulam according to bearing load will influence the failure behavior of bolted connection, and estimating the shear yield strength of the bolted connection of the reinforced glulam is necessary, not only by using the bearing strength characteristics but also using the fracture toughness of the reinforced glulam.

Design of Elastomeric Bearing System and Analysis of it Mechanical Properties

  • Moon, Byung-Young;Kang, Gyung-Ju;Kang, Beom-Soo;Cho, Dae-Seung
    • Journal of Mechanical Science and Technology
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    • v.18 no.1
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    • pp.20-29
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    • 2004
  • This paper proposes a new type of bearing system. In this study, a method for design of on elastomeric bearing system and its mechanical property analysis are carried. Experimental and theoretical studies of the elastomeric bearings with fiber reinforcement were proved effective new lightweight bearing system. The fibers in the bearings for isolation are assumed to be flexible in extension, in contrast to the steel plates in the conventional bearing system. Several kinds of bearing systems in the form of long strips are designed, fabricated and tested. The results suggest that it is possible to produce the economical and effective fiber-reinforced elastomeric bearing that matches the behavior of a steel-reinforced bearing. Feasibility and advantages of the proposed bearings are illustrated by the application of the analytic procedure to the structure system. Results obtained here are reported to be an efficient approach with respect to bearing system and design of bearing against shock absorbing system when compared with other conventional one.