Estimation of Kinematics and Loop Stiffness for Multi-Axis Machine Tool

이성철(Sungcheul Lee),황주호(Jooho Hwang),박천홍(Chun-Hong Park) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.5

Various types of 5-axis machine tools have been developed. In the case of a machine tool composed from linear motion, the kinematic equation can be obtained easily and intuitively. However, machine tools with more than four axes, including rotating axes, have generally performed kinematic and dynamic performance analyses using mathematical methods. In this paper, the kinematic equations of various types of machine tools are obtained, based on the Homogeneous Transformation Matrix method. The loop stiffness was then calculated as a mathematical model. A mathematical model of loop stiffness was verified by using a method to calculate the loop stiffness of a commercial program. The results of the mathematical model showed less than a 1% error with the commercial program, and this could show the validity of the mathematical model. Then, this model was applied to two types of machine tools. The minimum loop stiffness of both models is compared.

대형 선박의 파이프 루프 최적구조설계(Ⅰ)

박치모(CHI-MO PARK),장대오(DAE-OH JANG),한삼덕(SAM-DUCK HAN) 한국해양공학회 2007 韓國海洋工學會誌 Vol.21 No.5

Ship structures are subject to severe environmental loads causing appreciable hull girder deflection which in tum affects the piping system attached to the main hull in the form of displacement load. While this load may cause failure in the pipes, loops have been widely adopted as a measure of preventing this failure with the idea that they may lower the stress level in a pipe by absorbing some portion of the displacement load. But as the loops also have some negative effects such as causing extra manufacture cost, deteriorating the function of the pipe and occupying extra space, the number and the dimensions of the loops adopted need to be minimized. This research develops a design formula for pipe loops. The accuracy of the proposed design formula was verified by comparing two results respectively obtained by the proposed formula and MSC/NASTRAN. The paper ends with the sample example showing the efficiency of the proposed formula.

무심연삭기 주축계의 설계 및 성능평가

박천홍(Chun Hong Park),황주호(Joo Ho Hwang),조순주(Soon Joo Cho),조창래(Chang Rae Cho) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.11

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/㎛, which was enough to machine the ferrule. Rotational accuracies of each spindle were about 0.2 urn 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 ℃ in the case of grinding spindle and 1.8 ℃ 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.

초정밀 무심연삭기 운동요소 평가

박천홍(Chun-hong Park),황주호(Jooho Hwang),조순주(Soon-Joo Cho),조창래(Chang-Rae Cho) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

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 was performed in this paper. Layout and details of spindle system was 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/㎛, which was enough to machine the ferrule. Rotational accuracies of each spindle were about 0.2 ㎛ 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 ℃ in the case of grinding spindle and 1.8 ℃ 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.

포일 스러스트 베어링의 정하중 구조 강성과 손실계수 측정

류근(Keun Ryu),이호원(Howon Yi) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.10

벽식구조 복합화 공법개발에 따른 외부 수평접합부의 휨성능에 관한 연구

배규웅(Bae Kyu-woong),박금성(Park Keum-Sung),이종민(Lee Jong-Min),김영길(KimYoung-Kil),류재천(Ryu Jai-Chon) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.3

The purpose of this study is to develop the hybrid method for apartment with shear wall structure, which combines merits of the existing precast concrete members and in-situ concrete members. The developed hybrid method is composed of PC wall and half PC slab(HP) or in-situ slab(RPA, RPB). The specimens are schemed to insure flexible capacity of external horizontal joints. This paper presents an experimental investigation on the flexible capacity of external horizontal joints in the developed hybrid wall joint system. Based on the experimental results, it makes that the moment distributed to the end of slab with hybrid method must be considered at the rate of initial stiffness and reflected to calculate the deflection of slab center. Also, it is shown that the performance of the external horizontal joint between the all PC wall and the in-situ slab(RPA, RPB) is more excellent than that of existing in-situ concrete members(RR) in respect of strength, failure mode, loop stiffness and energy capacity.

대형 선박의 파이프 루프 설계식 개발 (Ⅰ)

박치모(CHI-MO PARK),양박달치(PARK-DAL-CHI YANG),이종훈(JONG-HOON LEE) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.5

Ship structures are subject to severe environmental loads causing appreciable hull girder bending, which in turn affects the piping system attached to the main hull in the form of a displacement load. While this load may cause failure in the pipes, loops have been widely adopted as a means of preventing this failure, with the idea that they may lower the stress level in a pipe by absorbing some portionof the displacement load. But since such loops also have some negative effects, such as causing extra manufacturing cost, deteriorating the function of the pipe, and occupying extra space, the number and dimensions of the loops adopted need to be minimized. This research developed design formulas for pipe loops, modeling them as frames composed of beam elements, where not only bending but also shear deflection is taken into account. The accuracy of the proposed design formulas was verified by comparing two results respectively obtained by the proposed formulas and MSC/NASTRAN. The paper concludes with a sample example showing the efficiency of the proposed formulas.

코너부 곡률을 고려한 선박용 파이프 루프 설계식 개발

박치모(Chi-Mo Park),양박달치(Park-Dal-Chi Yang) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.4

Many longitudinally arranged pipes in ships are subject to considerable displacement loads caused by the hull girder bending of ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been widely adopted as a measure to prevent such failure, with the idea that they can lower the stress level in a pipe by absorbing some portion of these loads. But since such loops have some negative effects, such as causing extra manufacturing cost and occupying extra space, the number and dimensions of the loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the effects of the curvature of loop corners and the flexibility of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results respectively obtained by the proposed formulas and MSC/NASTRAN. The paper ends with a sample application of the proposed formulas showing their efficiency.

대형 선박의 파이프 루프 설계식 개발(Ⅱ)

박치모(Chi-Mo Park),양박달치(Park-Dal-Chi Yang),이종훈(Jong-Hoon Lee) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.1

Many logitudinal pipes in ships are subject to considerable loads, caused by hull girder bending in the ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been waidely adopted to prevent such failure, based on the idea that they can lower the stress level in a pipe by absorbing some portion of these loads. But as the loops also have some negative effects, such as causing extra manufacturing cost, deteriorating the function of the pipe, and occupying extra space, the number and dimensions of these loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the flexibility effect of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results obtained from the proposed formulas and MSC/NASTRAN. This paper concludes with a sample application of the proposed formulas, shoing their efficiency.

지상차량의 롤모드 상에서 댐핑효과 향상을 위한 스티어링 제어에 관한 연구

소상균 한밭대학교 생산기반기술연구소 2001 생산기반기술연구소 논문집 Vol.1 No.1

For the high center of gravity vehicles the roll stiffness of their suspensions is arranged to be very high because such vehicles are in some danger of tipping over in cornering. In some cases, the effective roll stiffness is determined significantly by the compliance of the tires because of the very stiff anti-roll members incorporated in the suspension. Therefore, wind gusts and roadway unevenness may cause large swaying oscillations because the shock absorbers cannot provide effective damping of the roll mode. Here, a control scheme to augment the damping of the roll mode is proposed. The use of feedback signals related to roll motion to steer the front or rear wheels in such a way as to provide damping of the roll motion will be studied. The scheme is effective from moderate speeds to high speeds and stabilizes the roll mode without introducing disturbance moments from roadway unevenness as shock absorbers do.