• Title/Summary/Keyword: Spindle System

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Vibration Compensation due to Spindle Unbalance using An Electro Magnetic Exciter (전자기 가진기를 이용한 스핀들 불평형 진동 보상)

  • 안재삼;김선민;이선규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.505-509
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    • 2001
  • When the spindle is rotated for machining the workpiece, the vibration is generated due to the spindle unbalance. This vibration affects surface finish, dimensional accuracy, tool life, and spindle bearings. To compensate this effect of the spindle unbalance, the spindle system using an EME(electro magnetic exciter)is proposed in this paper. In the proposed spindle system, the vibration due to the spindle unbalance is monitored using vibration sensors and is compensated by electromagnetic attractive forces generated in the EME which are excited by anti-direction forces corresponded with the measured unbalance. Firstly, the spindle system using an EME and control system are constructed to compensate the effect of spindle unbalance in this paper. And then the system is modeled by bond graph to analyze the system. Finally, a controller for vibration compensation due to spindle unbalance is designed and is implemented in real experimental system. As a result, experimental results show this proposed spindle system is very effective to compensate the spindle unbalance.

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An Experimental Study on the Rotational Performances of NC Lathe Spindle System (NC 선반주축 의 회전성능 향상 을 위한 실험적 연구)

  • 이형식;이봉진;송기무
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.1
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    • pp.86-94
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    • 1984
  • In order to improve the rotational performances of NC lathe spindle system in high speed range, a new type(Floating-type driven by V-belt)spindle system was optimally designed and experimented. Through the results of the experiments, the rotational performances of the new type spindle system was discussed and compared with the three equivalent conventional lathe spindle systems. The spindle rotational accuracy( radial error motion of spindle axis), the accelation and the temperature rise of the front spindle bearings for the non-cutting operation were considered as the spindle rotational performances. The radial error motion of the spindle axis was measured by applying the modified L.R.L. method. Compared with the equivalent conventional spindle systems, the following results were obtained. (1) The new type spindle system reduces the radial error motion of the spindle axis in high speed range(1800rpm-2000rpm). (2) The new type spindle system reduces the acceleration and the temperature rise of the spindle bearings considerably with increasing the spindle speed. It is also confirmed that, by this new type spindle system, the max. allowable speed can be increased with satisfying the spindle rotational performances.

Design and Performance Evaluation of a Spindle System for Centerless Grinding Machine (무심연삭기 주축계의 설계 및 성능평가)

  • Park Chun Hong;Hwang Joo Ho;Cho Soon Joo;Cho Chang Rae
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.11 s.176
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    • pp.142-150
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    • 2005
  • Design and performance evaluation of a spindle system which was composed of a grinding spindle and a regulating spindle for the centerless grinding of ferrule were performed in this paper. Layout and details of spindle system were designed and hydrostatic bearings for spindles were also designed. Prototype of spindle system was developed and its availabilities to machine the ferrule were discussed using the experimental results on the spindle stiffness of each spindle, loop stiffness, rotational accuracy and thermal characteristics. Loop stiffness of the spindle system was $130\;N/{\mu}m$, which was enough to machine the ferrule. Rotational accuracies of each spindle were about $0.2{\mu}m$ at the primary speed of 2,300 rpm(grinding spindle) and 300 rpm(regulating spindle). Temperature rises at the same speed were about $4.4\~4.7^{\circ}C$ in the case of grinding spindle and $1.8^{\circ}C$ in the case of regulating spindle, which agreed well with the designed value. From these results, it was estimated that the prototype of spindle system had enough performances for the centerless grinding machine to machine the ferrule.

Structural Characteristics Analysis System "SpindleX" for Machine-Tool Spindle System (공작기계 주축계의 구조특성 해석시스템 SpindleX)

  • 김석일;조재완;이원재
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.1016-1020
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    • 2000
  • In this study, a structural characteristics analysis system for motor-integrated high-speed spindle systems, “SpindleX”, is developed based on the Timoshenko theory and the multi-layered finite element method. Since “SpindleX” has the various analysis modules related to static deflection analysis, modal analysis, frequency response analysis, unbalance response analysis and so on, it is useful in performing systematically and quantitatively the design and evaluation processes of spindle system under the windows GUI environment. Also, to enhance the user-friendliness, “SpindleX” possesses the various additional functions such as the DXF file interface for auto-importing the shape and geometric data of spindle system from the DXF file, the bearing database for auto-importing the mechanical properties and geometric data of bearing by the bearing number, and the graphical visualization for certificating the imported and analysed data of spindle system.

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Thermal Characteristics Analysis of a High-Speed Motor-Separated Spindle System Using Oil-Jet Lubrication Method (오일-제트 윤활 방식의 모터 분리형 초고속 주축계의 열 특성 해석)

  • 김석일;김기태
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.1
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    • pp.69-75
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    • 2004
  • This paper presents the thermal characteristics analysis of a high-speed motor-separated spindle system consisted of angular contact ball bearings and built-in motor with oil-jet lubrication. The spindle system is composed of the main spindle and sub-spindle which are mechanically connected by a flexible coupling. The spindles are supported by two front and rear bearings, and the built-in motor is located between the front and rear bearings of the sub-spindle. The thermal analysis model of spindle system is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on temperature distribution and heat flow under the various testing conditions related to material of bearing ball, spindle speed and coolant temperature.

Design and Estimation of a Spindle System for Centerless Grinding Machine (무심연삭기 주축계의 설계 및 성능평가)

  • Park C.H.;Hwang J.H.;Oh Y.J.;Cho S.J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.86-89
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    • 2005
  • Design and estimation of a spindle system which was composed of grinding spindle and regulating spindle for the centerless grinding of ferrule was performed and prototypes of each spindle were manufactured. Loop stiffness of the spindle system was 130 N/${\mu}m$. Although the value was lower than the target value of 150 N/${\mu}m$, as there included 20% of the safety factor, it was enough to machine the ferrule. Rotational accuracies of each spindle were about 0.2${\mu}m$ at the primary speed of 2,300 rpm(grinding spindle) and 300 rpm(regulating spindle). Temperature rises at the same speed were about $4.4\;\~\;4.7^{\circ}C$ in the case of grinding spindle and $1.8^{\circ}C$in the case of regulating spindle, which were well agreed with the designed value. From these results, it was estimated that the prototype of spindle system had a enough performances for the centerless grinding machine to machine the ferrule.

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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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Oil-Air Lubrication Characteristics of a High Speed Spindle System for Machine Tools(I) Effect of Oil Supply Rate, Rotational Spindle Speed and Spindle System Structure (공작기계용 고속주축계의 오일에어윤활특성에 관한 연구 (I) 공급유량, 주축회전수 및 주축계 구조의 영향)

  • 김석일;최대봉;박경호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.2
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    • pp.351-358
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    • 1993
  • Recently a high speed spindle system for machine tools has attracted considerable attention to reduce the machining time, to improve the machining accuracy, to perform the machining of light metals and hard materials and to unite the cutting and grinding processes. In this study, a high speed spindle system is developed by applying the oil-air lubrication method, angular contact ball bearings, injection nozzles with dual orifices and so on. And a lubrication experiment for evaluating the performance of the spindle system is carried out. Especially, in order to establish the lubrication conditions related to the development of a high speed spindle system, the effects of oil supply rate, rotational spindle speed and so on are studied and discussed on the bearing temperature rise, bearing temperature distribution and frictional torque. And the effect of spindle system structure on the bearing temperature distribution is investigated.

Effect on the Compliance of Spindle -Bearing System by the Assembling Tolerance (축-베어링계의 컴플라이언스 특성에 미치는 조립공차의 영향)

  • 이강재;서장력;이선규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.995-999
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    • 1995
  • In spindle-bearing system, the displacement characteristics of the bearing by the load applied on the spindle are affected greatly by the assembling tolerance between the spindle and housing assembled to support the bearing. Also in spindle system of rotational operation, the compliance characteristic of the bearing is expected to be varied frequently by the thermal deformation of the spindle and the housing. To predict the thermal deformation of the spindle including heat generation of the bearing, we need to examine the effect on the compliance of spindle-bearing system by the assembling tolerance. In this paper, we proposed the load-displacement relation expression considering the effect which the variation of contact pressure due to the radial directional assembling tolerance between the bearing and the housing influences on the axial and radial directional displacement characteristics of the bearing. Furthermore, for several assembling systems of bearings and housings having all different assembling tolerances, we proposed a method to predict exactly the variation of the bearing preload which is sensitive to the thermal deformation by showing the propriety with experimental results.

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Development of Inductive Sensor in Magnetic Bearing Spindle System (자기 베어링 주축시스템의 유도형 센서 개발)

  • Shin, Woo-Cheol;Lee, Dong-Ju;Hong, Jun-Hee;Noh, Myoung-Gyu
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.10a
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    • pp.32-37
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    • 2000
  • In a high speed spindle system, it is very important to monitor the operation of the spindle to prevent catastrophic damage to the system. Widely used sensors for monitoring are eddy-current and capacitive types. These sensors provide high accuracy of monitoring, but their steep prices lead to expensive high speed spindle system. The main god of our research is to develop technology to produce high speed spindle system utilizing magnetic bearings. As active magnetic bearings require position sensors for feedback control, a noncontact position sensor is bang developed as a part of this main goal. Once developed, it will contribute to affordable high speed spindle system. In this paper, we report the selection process of the sensor types and the experimental results with driving circuits.

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