정면밀링공정중 주축모터전류를 이용한 절입비의 실시간 추정

조규진,오영탁,권원태,주종남 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.6

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ratio using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to the cutting torque acting on a single tooth at the swept angle of cut and can be acquired from cutting torque signals. Average cutting torque per revolu-tion can also be calculated from cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting con-ditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spin-dle motor current. Varying immersion ratio is also estimated well using the presented algorithm.

정면밀링공정중 추축모터전류를 이용한 절입비의 실시간 추정

조규진,오영탁,권원태,주종남 한국생산제조학회 2000 한국공작기계학회지 Vol.9 No.6

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ratio using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to the cutting torque acting on a single tooth at the swept angle of cut and can be acquired from cutting torque signals. Average cutting torque per revolution can also be calculated from cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current. Varying immersion ratio is also estimated well using the presented algorithm.

Estimation of the Cutting Torque Without a Speed Sensor During CNC Turning

Kwon, Won-Tae,Hong, Ik-Jun The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.12

In this paper, the cutting torque of a CNC machine tool during machining is monitored through the internet. To estimate the cutting torque precisely, the spindle driving system is divided into two parts: electrical induction motor part and mechanical part. A magnetized current is calculated from the measured three-phase stator currents and used for the total torque estimation generated by a spindle motor. Slip angular velocity is calculated from the magnetized current directly, which gets rid of the necessity of a spindle speed sensor. Since the frictional torque changes according to the cutting torque and the spindle rotational speed, an experiment is adopted to obtain the frictional torque as a function of the cutting torque and the spindle rotation speed. Then the cutting torque can be calculated by solving a $2^{nd}$ order difference equation at a given cutting condition. A graphical programming method is used to implement the torque monitoring system developed in this study to the computer and at the same time monitor the torque of the spindle motor in real time through the internet. The cutting torque of the CNC lathe is estimated well within an about $3\%$ error range in average in various cutting conditions.

인터넷을 이용한 CNC 선반의 속도 센서리스 토크감시

홍익준(Ik Jun Hong),권원태(Won Tae Kwon) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.5

Internet provides the useful method to monitor the current states of the machine tool no matter where a personnel monitors it. In this paper, a monitoring method of the torque of the machine tool's spindle induction motor using internet is suggested. To estimate the torque accurately, spindle driving system of an CNC lathe is divide into two parts, induction motor part and mechanical part attached to the induction motor spindle. Magnetizing current is calculated from the measured 3 phase currents without speed sensor used to estimate the torque generated by an induction motor. In mechanical part of the system, some of the torque is used to overcome friction and remaining torque is used to overcome cutting force. An equation to estimate friction torque is drawn as a function of cutting torque and rotation speed. Graphical programming is used to implement the suggested algorithm, to monitor the torque of an induction motor in real time and to make the estimated torque monitored on client computers. Torque of the spindle induction motor is well monitored on the client computers in about 3% error range under various cutting conditions.

A Theory Thermal Growth Control Techniques of High Speed Spindles

Chang,Ching-Feng,Ling,Chao-Shui,Chao, Ching-Yi,Chen, Jin-Jia,Chen,Tsair-Rong 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

A motorized high speed spindle has very complicated dynamics consisting of non-stationary and speed-related thermal characteristics. Many studies have been reported with different designs to control or monitor spindle’s thermal growth with limited results, whereas the application of High Speed Machining (HSM) demands “zero tolerance”no matter the range of speed or material to be machined. This paper proposes a direct displacement measuring system, which is a considerable improvement as compared with many taking inaccurate readings through a traditional thermo coupler, to accurately monitor and compensate the thermal growth associated with motorized high speed spindles. This direct displacement measuring system optimizing a high speed synchronous feedback system will meet the tolerance and performance expected in HSM applications. Based on the introduction of Foucault current, a design for an accurate thermal growth is outlined.

주축 모터를 이용한 포터블 자동 면취기의 가공 안정성 진단

김태영 ( Tae Young Kim ),안병훈 ( Byeong Hun An ),김화영 ( Hwa Young Kim ) 한국센서학회 2022 센서학회지 Vol.31 No.1

This study describes a system that monitors the tool and cutting state of automatic beveling operation in real time. As a signal for cutting state monitoring, a motor current detected from the spindle drive system of the automatic beveling machine is used to monitor abnormal state. Because automatic beveling is processed using a face milling cutter, the cutting force mechanism is the same as the milling process. The predicted cutting torque is obtained using a cutting force model based on specific cutting resistance. Then, the predicted cutting torque is converted into the spindle motor current value, and cutting state stability is diagnosed by comparing it with the motor current value detected during beveling operation. The experimental results show that the spindle motor current can detect abnormal cutting state such as overload and tool wear during beveling operation, and can diagnose the cutting stability using the proposed equipcurrent line diagram.

머시닝 센터에서 절삭조건 변화에 따른 절삭력 추종제어의 DSP보드 응용

권원태 서울시립대학교 산업기술연구소 1997 산업기술연구소논문집 Vol.5 No.-

Spindle motor current is used to estimate the cutting force indirectly and contol the feed rate for the cutting force regulation, To assure the reliability of the system including DSP board, experiments under varying cutting condition are carried out. It is shown that the cutting force is regulated well during machining of tapered or stepped workpiece and circular shaped workpiece of changing depth of cut. The software to make the DSP board communicate with host computer is coded under Window 95 environment and implemented to the system. The experiments show that the DSP board recognizes the information of installed cutting tool and cutting conditions and uses it for the proper control of the feed rate. Dependability of the whole system under production environment is assured by many experiments.

CFRP 가공에서의 절삭 토크 추정을 위한 스핀들 모터 전류 주파수 분석

박동섭(Dong Sub Park),정영훈(Young Hun Jeong) 한국가시화정보학회 2016 한국가시화정보학회 학술발표대회 논문집 Vol.2016 No.12

밀링가공 중 주축 모터 전류 분석을 통한 가공 상태 식별에 관한 연구

김재혁(J. H. Kim),최영재(Y. J. Choi) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월

밀링 가공은 회전하는 공구가 피삭재에 닿으면서 진행된다. 가공이 진행되는 구간에서 발생하는 물리적 신호를 센서 등을 통해 취득하면 공구파손, 충돌 등 이상가공 탐지에 활용할 수 있고, 절삭력 추정, 절삭계수 추출 등 다양한 가공 관련 모니터링 기능 개발에 활용이 가능하다. 하지만 비가공 구간의 신호가 앞서 언급한 모니터링 기능 구현 시 방해요인으로 작용하여 가공/비가공 상태를 정확히 구분해야 하고, 이를 위해 가공프로그램, 좌표, 센서 신호 등을 사용한다. 본 연구에서는 가공 부하에 따라 모터의 소비전류가 변화하는 관계를 이용하여 전류센서를 통해 취득한 신호를 가공 상태 구분에 활용하였다. 전류신호는 가공시 주축에 동력을 전달하는 주축 모터에 전원을 공급하는 서보드라이버 출력 부분에 전류센서를 장착하여 취득하였고, DAQ 를 통해 신호를 변환하였다. 소비전류를 통해 가공 상태를 구분하기 위해 알루미늄 합금을 대상으로, 3 날 10 파이, 평엔드밀을 이용하여 숄더링 가공 실험을 수행하였으며, CNC 에서 취득한 스핀들부하와 공구동력계를 이용하여 절삭력을 함께 수집하며 비교 분석하였다. 실험결과, 약 100 N 의 절삭력이 발생하는 가공구간에서 기준이 되는 공구동력계 신호의 경우 가공, 비가공 상태가 명확하게 구별되는 반면, 스핀들부하는 가공 시 부하가 비가공 구간보다 더 낮아지는 경우가 발생하여 가공상태를 구별하기 어려웠다. 스핀들 전류 또한 비가공 시 전류의 수치가 낮아지는 현상이 발생하여 가공 상태 구분을 위해 추가 주파수 분석을 수행하였다. 전류의 주파수 분석 결과, 주파수 분석결과 가공 주파수는 비가공 주파수에 비해 상대적으로 높아지는 것을 확인하였고, 높아진 가공 주파수 범위로 필터링을 수행하였다. 필터링한 전류신호를 실효값(RMS)을 처리한 결과, 낮은 가공부하에서의 가공 상태 구분이 가능하였다.

주축모터 전류를 통한 절삭력의 간접 측정 및 절삭력 추종제어

김기대(Gi D. Kim),권원태(Won T. Kwon),주종남(Chong N. Chu) Korean Society for Precision Engineering 1997 한국정밀공학회지 Vol.14 No.10