• Title/Summary/Keyword: 이송속도 제어

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Modeling and Dynamic Analysis of Electro-mechanical System in Machine Tools(2$^{nd}$ Report) - Modeling and Dynamic Analysis of Feed Drive System - (공작기계 시스템의 모델링과 동적특성 분석 (제2보) - 이송계의 모델링과 동적특성 분석 -)

  • Park, Yong-Hwan;Shin, Heung-Chul;Moon, Hee-Sung;Choe, Song-Yul
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.2 s.95
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    • pp.218-224
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    • 1999
  • In the feed drive systems of machine tools that consist of many mechanical components such as motor, coupling, ballscrew, nut or table, a torsional vibration is often generated because of its elastic elements in torque transmission. Generally, the accuracy of motion control system is strongly influenced by the dynamic behavior of coupled transmission components. Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So, it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed system. In this paper, the mathematical model of a feed drive system was developed and its mechanical characteristics were analyzed on the basis of the proposed model. The design concepts of speed control loop to stabilize a feed drive system were also proposed.

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A Study on Improvement of WC Core Surface Roughness by Feedrate Control (Feedrate Control에 의한 초경코어 표면조도 향상에 관한 연구)

  • Kim, Hyun-Uk;Jeong, Sang-Hwa;Lee, Dong-Kil;Kim, Sang-Suk;Kim, Hye-Jeong;Kim, Jeong-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.1
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    • pp.57-62
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    • 2009
  • Recently, with the increasing lightness and miniaturization of high resolution camera phones, the demand for aspheric glass lens has increased because plastic and spherical lens are unable to satisfy the required performance. An aspheric glass lens is fabricated by the high temperature and pressure molding using a tungsten carbide molding core, so precision grinding technology for the molding core surface are required. This paper reports a development of feedrate control grinding method for aspherical molding core using parallel grinding method. A plane molding core was ground using conventional and feedrate control grinding method. The performance of the feedrate control method was evaluated by measurement of surface roughness. The result indicated that the average surface roughness was reduced to 1.5 nm, which is more efficient than the conventional grinding method.

Integrated NURBS Surface Interpolator Considering Both Rough and Finish Cuts (황삭 및 정삭을 고려한 통합형 NURBS 곡면 인터폴레이터)

  • Koo, Tae-Hoon;Jee, Sung-Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.11
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    • pp.1958-1966
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    • 2003
  • Three-axis CNC surface machining entails a series of processes including rough cutting, intermediate cutting and finish cutting for a reference surface defined in CAD/CAM. This study is targeting development of an integrated NURBS surface interpolator that can incorporate rough, intermediate and finish cutting processes. In each process, volume to be removed and cutting condition are different according to the shape of a part to be machined and the reference surface. Accordingly, the proposed NURBS surface interpolator controls motion in real-time optimized for the machining conditions of each process. In this paper, a newly defined set of G-codes is proposed such that NURBS surface machining through CNC is feasible with minimal information on the surface composition. To verify the usefulness of the proposed interpolator, through computer simulations on NURBS surface machining, total machining time, size of required NC data and cutting force variations are compared with the existing method.

Selection of Main Factors by Experimental Analysis for Profile Blast Machining Based on Microparticle Blasting Equipment with a Two-Axis Sequence Control Stage (2축 시퀀스 제어 스테이지와 미세입자 분사장치에 의한 형상 분사가공시 실험계획법에 의한 주요인자 검출)

  • Hwang, Chul-Woong;Lee, Sea-Han;Wang, Duck Hyun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.11
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    • pp.64-69
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    • 2020
  • To determine the effective factors for microparticle blasting with precise sequence position control in the x-axis and y-axis directions, we conducted a statistical experimental analysis of blasted square shapes by considering five condition factors. The control input and output were operated simultaneously by rotation-linear motion conversion and fine particles were blasted onto the aluminum specimen by precise position control driving using multiple execution codes. The micro-driving device used for processing was capable of microparticle blasting and of controlling the system through contact with a limit sensor at high speed and a two-degree-of-freedom driving mechanism. Our experiments were conducted on 1,050 specimens of pure aluminum (containing <1% of other elements). The effects of several factors (e.g., particle and nozzle diameters, blasting pressure, and federate and blasting cycle numbers) on the surface roughness and blasted surface's depth were verified through a statistical experimental analysis by applying the dispersion analysis method. This statistical analysis revealed that the nozzle diameter, the blasting pressure, and the blasting cycle number were the dominant factors.

Robust Optimization of the Solenoid Assembly in Electromagnetic Limited Slip Differential by Considering the Uncertainties in Machining Variables (가공변수의 불확실성을 고려한 전자제어식 차동제한장치 솔레노이드 어셈블리의 강건 최적설계)

  • Oh, Sang-Kyun;Lee, Kwang-Ki;Suh, Chang-Hee;Jung, Yun-Chul;Kim, Young-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.10
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    • pp.1307-1313
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    • 2011
  • The mechanical limited slip differential (LSD) in vehicles is being replaced by the electromagnetic LSD because of its fast response and better active control characteristics. The coil housing made of STS 304 is one of the most important parts in the solenoid assembly of the electromagnetic LSD. High geometrical accuracy is a prerequisite for the manufacture of such coil housings, but precision machining is difficult because of the use of STS 304 thin plate and the variance in machining variables. The aim of this study is to optimize the mean and variance of the shape accuracy in the coil housing by finding a robust solution for the machining process conditions. The mean and standard deviation of the jaw contact pressure, cutting speed, and feed rate are considered to be the major parameters for minimizing the geometrical mean and variance. The response surface model based on the second-order Taylor series is combined together to minimize the mean and variance of the shape accuracy of the coil housing.

Control of a CNC Machining Center Using the Indirect Measurement of the Cutting Force (절삭력 간접 측정을 이용한 CNC공작기계 제어)

  • 송진일;손주형;권동수;김성권
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.11
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    • pp.9-20
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    • 1998
  • In recent manufacturing process, the increase of productivity has been attempted by reducing machining time with the increase of cutting force. However, the excessive increase of cutting force can cause tool breakage and have a bad effect on both manufacturing machine and workpiece. Thus, it is necessary to estimate and control the cutting force in real time during the process. In this study, use of disturbance observer is proposed for the indirect cutting force estimation. The estimated cutting force is used for the real-time control of feedrate, making the actual cutting force follow the reference force command. Since the suggested method does not need an expensive sensor like a dynamometer, the method is expected to be used practically. Since the actual cutting force follow the reference force, resulting the reducing of the machining time the increase of productivity are also expected, and the quality of cutting surface has been improved due to the adjusted feedrate. Besides, an actual constant cutting force guarantees the prevention of tool breakage. To show the effectiveness of the suggested cutting force control method, an experimental setup has been made without sensor and applied to several workpieces. Experiments show that the suggested method is effective to cutting force control of a CNC machining center.

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Development and Verification of the Automated Cow-Feeding System Driven by AGV (무인이송로봇기반 자동 소사료 공급 시스템 개발 및 검증)

  • Ahn, Sung-Su;Lee, Yong-Chan;Yoo, Ji-Hun;Lee, Yun-Jung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.3
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    • pp.232-241
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    • 2017
  • This paper presents an automated cow-feeding system based on an AGV and screw conveyor for domestic livestock farms, which are becoming larger and more commercialized. The system includes a hopper module for loading pellet-type mixed feed at the top of the system, a transfer module mounted with a screw conveyor to transfer feed from the hopper module to the outlet module, an outlet module composed of belt conveyors, and an electromagnetic guided driving-type AGV. The weight of the loaded feed is measured by a load cell located under the transfer module. The system reads the feed discharge information stored in RFID tags installed in each cowshed cell, and a predetermined amount of feed is discharged while the AGV is moving. A cow-feed test system was constructed to determine the design parameters of the screw conveyor in the transfer module that determine the feeding capacity. These parameters include the screw's outer diameter, the screw shaft outer diameter, and screw pitch. The parameters were applied to the finalized cow-feed system construction. A DSP-based main controller and cow-feeding algorithm for different scenarios were also developed to control the system. Experimental results confirmed that the system could supply a total of 21 kg of feed uniformly at 420 g/s for a cowshed cell which has 7 cows. The driving distance was 5 m and the speed was 0.1 m/s. Thus, the proposed system could be applied to standardized domestic livestock farms.

NURBS Curve Interpolator for Controlling the Surface Roughness (표면거칠기를 고려한 NURBS 곡선보간기)

  • Choi In hugh;Jung Tae sung;Yang Min Yang;Lee Dong yoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.5 s.236
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    • pp.698-706
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    • 2005
  • Finish machining of a curved surface is often carried out by an NC system with curve interpolation in the field. This NURBS interpolation adopts a feedrate optimizing strategy based on both the geometrical information and dynamic properties. In case of a finish cut using a ball-end mill, the curve interpolator needs to take the machining process into account for more improved surface, while reducing the polishing time. In this study, the effect of low machinability at the bottom of a tool on surface roughness is also considered. A particular curve interpolation algorithm is proposed fur generating feedrate commands which are able to control the roughness of a curved surface. The simulation of the machined surface by the proposed algorithm was carried out, and experimental results are presented.

Study on Speed Ripple Reduction Algorithm in Sensorless Controlled IPMSM (IPMSM 센서리스 제어에서의 속도리플저감 알고리즘에 관한 연구)

  • Lee, Song-Cheol;Jung, Young-Seok
    • The Transactions of the Korean Institute of Power Electronics
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    • v.21 no.3
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    • pp.249-253
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    • 2016
  • In this study, a harmonic-pulsation-compensator (HPC) is presented to reduce a periodic speed ripple in IPMSM. A proportional-integral compensator in HPC is proposed instead of the existing integral compensator to reduce the speed ripple more rapidly. A formula to calculate a rotation angle is also proposed, making compensation optimal in sensored and sensorless controls. The validity of the proposed algorithm is verified by experiments.

Cutting Force Control by Variable Feed and Spindle Speed in Ball-end Milling Process (이송 및 주축속도 가변속에 의한 볼 엔드밀 절삭공정의 절삭력 추적제어)

  • Lee, Chun-Hwan;Yi, Seung-Ug;Lee, Gun-Bok
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.4
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    • pp.73-80
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    • 1993
  • There and two important variables in machining process control, which are feed and cutting speed. It is possible to improve the machining accuracy and the productivity by maintaining the optimal feed and cutting speed. In this work, a controller is designed to achieve on-line cutting force control based on the modeling of cutting process dynamics established through step response test. Two schemes are proposed and implemented. The first is feed control under the constant spindle speed and the second is spindle speed control under the constant feed. Finally, both are proved to work properly through simulation and experimentation.

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