Knowledge-Evolutionary Intelligent Machine-Tools

Dong-Hoon Kim,Jun-Yeob Song 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.11

In FMS (Flexible Manufacturing System) and CIM (Computer Integrated Manufacturing), machine-tools have been the target of integration in the last three decades. The conventional concept of integration is being changed into the autonomous manufacturing device based on the knowledge evolution by applying advanced information technology in which an open architecture controller, high-speed network and internet technology are included. In the advanced environment, the machine-tools is not the target of integration anymore, but has been the key subject of cooperation. In the near future, machine-tools will be more improved in the form of a knowledge-evolutionary intelligent device. The final goal of this study is to develop an intelligent machine having knowledge-evolution capability and a management system based on internet operability. The knowledge-evolutionary intelligent machine-tools is expected to gather knowledge autonomically, by producing knowledge, understanding knowledge, reasoning knowledge, making a new decision, dialoguing with other machines, etc. The concept of the knowledge-evolutionary intelligent machine is originated from the machine control being operated by human experts’ sense, dialogue and decision. The structure of knowledge evolution in M2M (Machine to Machine) and the scheme for a dialogue agent among agent-based modules such as a sensory agent, a dialogue agent and an expert system (decision support agent) are presented in this paper, with intent to develop the knowledge-evolutionary machine-tools. The dialogue agent functions as an interface for inter-machine cooperation. To design the dialogue agent module in an M2M environment, FIPA (Foundation of Intelligent Physical Agent) standard platform and the ping agent based on FIPA are analyzed in this study. In addition, the dialogue agent is designed and applied to recommend cutting conditions and thermal error compensation in a tapping machine. The knowledge-evolutionary machine-tools are expected easily implemented on the basis of this study and shows a good assistance to sensory and decision support agents.

한-EU FTA와 한국 공작기계의 대 EU 수출변화

박구웅 한국무역통상학회 2020 무역통상학회지 Vol.20 No.1

Machine tools are called mother machine symbolizing the status as a backbone of the whole machinery industry. Among the major machine tools are machining center, lathe, drilling machine, grinding machine, presses and forging machines. Main upstream industries of machine tools are forging, moulding, heat treatment, precision measurements, noise/vibration control, electronic controls and CAD/CAM, while the main downstream industries are machinery, automobiles, aviation, electronics, and shipbuilding to name a few. We study the changes in Korean machine tool trade competitiveness with the European Union(EU) following the enactment of Korea-EU FTA on July 1st 2011. Korean machine tool export volume to the EU has increased from 0.16% of total exports to the EU in 1991 to 1.13% in 2018 while import volume of Korean machine tools from the EU decreased from 1.80% of total imports from the region in 1991 to 0.41% in 2018. For the analysis of changes in the international competitiveness of Korean machine tool industry, we have applied various indices and included the US, China, Japan and Germany in the sample. First, in terms of RCA(revealed comparative advantage), Korea ranked second with 3.102~4.771 after Japan with 7.457~9.852. Second, for TSI(trade specialization index), Korea showed a large variation among eight 4-digit HS codes(HS8456~HS8463). This indicates Korea is concentrating on a couple of key sub-groups of machine tools. Third, for CAC(comparative advantage by countries), we could find that Korea recorded the highest level both before and after the Korea-EU FTA with a large margin against major competing countries. Finally, in terms of ESI(export similarity index), Korea is competing in the EU market most fiercely with Japan and then with Germany and the US. Overall, following the Korea-EU FTA, Korean machine tool industry has improved her trade competitiveness against major producer countries by a noticeable difference.

Simulation-based machining condition optimization for machine tool energy consumption reduction

Lee, Wonkyun,Kim, Seong Hyeon,Park, Jaesang,Min, Byung-Kwon Elsevier 2017 JOURNAL OF CLEANER PRODUCTION Vol.150 No.-

<P><B>Abstract</B></P> <P>Optimizing the machining condition is one of the effective ways for reducing the energy consumption of machine tools at a unit process level. Based on statistical approaches with design of experiments, various methods have been developed to reduce the energy consumption by optimizing the machining condition. However, the methods cannot be easily utilized when the optimization target or machine tool design is modified because the optimal solution is determined based on the experimentally measured data. In this study, a simulation-based method that utilizes a virtual machine tool (VMT) to optimize the machining condition is proposed. The VMT model is designed to focus on estimating the energy consumption during machining and is developed by replicating real machine tools. Based on the VMT model, a genetic algorithm is used to optimize the machining condition to reduce the energy consumption. The changes in the optimization target or machine tool design are easily considered by modifying the cost function or component model, respectively. The proposed method is applied to reduce the energy consumption of a three-axis milling machine. The optimal feed rate and spindle speed are obtained for each line of the part program when the thrust force is limited. An experimental setup of the machine tool with an energy consumption monitoring system is constructed to demonstrate the effectiveness of the proposed method. The results show that the total energy consumption of the machine tool reduces by 13% owing to the optimization.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Simulation-based method to reduce the energy consumption of machine tool is proposed. </LI> <LI> Virtual machine tool to estimate the energy consumption during machining is built. </LI> <LI> Optimal machining conditions to minimize the energy consumption is obtained. </LI> <LI> Energy consumption reduction using proposed method is demonstrated experimentally. </LI> </UL> </P>

Quantitative evaluation method for machining accuracy retention of CNC machine tools considering degenerate trajectory fluctuation

Cong Feng,Zhaojun Yang,Chuanhai Chen,Jinyan Guo,Hailong Tian,Fanning Meng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

Accuracy retention is an important performance index of CNC machine tools. At present, research on the evaluation of machining accuracy retention of CNC machine tools mainly focuses on accuracy value of a fixed time point or different time periods, but studies on the fluctuation degree of degradation trajectory related to time change are limited. Extracting simple and effective degradation characteristics of machining accuracy and then evaluating machining accuracy retention considering fluctuation of degradation trajectory are necessary. The volume error model of CNC machine tools is established on the basis of multibody system theory in this study. Three-dimensional volume error vector is transformed into one-dimensional machining accuracy degradation by calculating offset distance between spatial error and origin points. Degradation data obtained via regular measurement and calculation are used to establish the complete degradation trajectory model of the CNC machine tools machining accuracy using radial basis function interpolation method according to the fluctuation degree of degradation trajectory, and concepts of average degradation rate and average degradation amount are defined. Lastly, examples showed that these two indicators can intuitively reflect fluctuation degree of machining accuracy degradation of CNC machine tools and effectively and quantitatively evaluate accuracy retention of CNC machine tools. The quantitative evaluation method of accuracy retention of CNC machine tools defined in this study considers the fluctuation degree of accuracy degradation trajectory. The quantitative evaluation index of accuracy retention demonstrates satisfactory engineering application because it can reflect not only the accuracy change of a single machine tool but also accurately compare the accuracy retention between different machine tools.

병렬 기구 공작 기계의 머신 시뮬레이션에 관한 연구

김기욱,정윤교,고해주,신혁,유한식 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

Recently, parallel kinematic machine tool with high accuracy and stiffness is causing great concern in 5-Axis processing which is applied in manufacturing with complicated shape products. However, there are some inherent difficulties in parallel kinematic machine tool such as a collision between workpiece and tool, over-cut and under-cut, verification of tool path route in progress. To solve these problem in advance, it needs machine simulation of parallel kinematic machine tool above all things. the purpose of this study is, therefore, carried out machine simulation for parallel kinematic machine tool and accumulation of technical knowledge for the productivity and efficiency in parallel kinematic machine tool through verification of 5-Axis machining.

Knowledge- Evolutionary Intelligent Machine-Tools - Part 1 : Design of Dialogue Agent based on Standard Platform

Kim, Dong-Hoon,Song, Jun-Yeob The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.11

In FMS (Flexible Manufacturing System) and CIM (Computer Integrated Manufacturing), machine-tools have been the target of integration in the last three decades. The conventional concept of integration is being changed into the autonomous manufacturing device based on the knowledge evolution by applying advanced information technology in which an open architecture controller, high-speed network and internet technology are included. In the advanced environment, the machine-tools is not the target of integration anymore, but has been the key subject of cooperation. In the near future, machine-tools will be more improved in the form of a knowledge-evolutionary intelligent device. The final goal of this study is to develop an intelligent machine having knowledge-evolution capability and a management system based on internet operability. The knowledge-evolutionary intelligent machine-tools is expected to gather knowledge autonomically, by producing knowledge, understanding knowledge, reasoning knowledge, making a new decision, dialoguing with other machines, etc. The concept of the knowledge-evolutionary intelligent machine is originated from the machine control being operated by human experts' sense, dialogue and decision. The structure of knowledge evolution in M2M (Machine to Machine) and the scheme for a dialogue agent among agent-based modules such as a sensory agent, a dialogue agent and an expert system (decision support agent) are presented in this paper, with intent to develop the knowledge-evolutionary machine-tools. The dialogue agent functions as an interface for inter-machine cooperation. To design the dialogue agent module in an M2M environment, FIPA (Foundation of Intelligent Physical Agent) standard platform and the ping agent based on FIPA are analyzed in this study. In addition, the dialogue agent is designed and applied to recommend cutting conditions and thermal error compensation in a tapping machine. The knowledge-evolutionary machine-tools are expected easily implemented on the basis of this study and shows a good assistance to sensory and decision support agents.

Exergy-based Energy Efficiency Evaluation Model for Machine Tools Considering Thermal Stability

Ben-jie Li,Huajun Cao,Bernard Hon,Lei Liu,Xi Gao 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.2

Machine tools, as the extensively used basic equipment of manufacturing industry, are characterized by intensive and inefficient energy consumption. With the launch and implementation of ISO 14955-1, energy efficiency has become an important criterion for machine tool evaluation. However, most ongoing research on energy efficiency evaluation of machine tools emphasizes on workpiece material removal energy efficiency and rarely considers energy consumption needed to ensure machining accuracy and accuracy consistency, especially energy consumption for thermal stability control of machine tools. In light of this, an exergy analysis based approach is presented to assess the comprehensive energy efficiency of machine tools, including energy consumption for material removal and thermal stability control. The key performance indexes of exergy efficiency, exergy destruction, and specific exergy consumption are analyzed. The feasibility of the proposed approach was demonstrated by a case study, in which the comprehensive energy efficiency of a machine tool was found to be 21.57% instead of 14.38% of material removal energy efficiency. The proposed method is more effective to evaluate the comprehensive energy efficiency, to support designers to design high-efficient machine tool and users to operate machine tool for green and precision machining.

가공정도 향상을 위한 Milling Machine의 안정화 설계

노승훈(Seung-Hoon Ro),이민수(Min-Su Lee),박근우(Keun-Woo Park),강희태(Hee-Tae Kang),이종형(Jong-Hyung Lee),양성현(Seong-Hyeon Yang) 한국산업융합학회 2011 한국산업융합학회 논문집 Vol.14 No.2

Since the most exclusive machines of the modern industries which require the nano precision rates are evolved from the machine tools, the design of the stable machine tool structure is very critical. Exclusive machines for the modern industries such as semiconductor, solar cell and LED have surface machining processes which are similar to the face cutting and grinding of conventional machine tools. This study was initiated to stabilize a milling machine structure and further to help design those exclusive machines which have similar machining mechanisms. The vibrations inherent to the machine tool structures hurt the precision machining as well as damage the longevity of the structures. There have been numerous researches in order to suppress the vibrations of machine tool structures using the extra modules such as actuators and dampers. In this paper, the dynamic properties are analyzed to obtain the natural frequencies and mode shapes of a machine tool structure which reflect the main reasons of the biggest vibrations under the given operating conditions. And the feasibility of improving the stability of the structure without using any additional apparatus has been investigated with minor design changes. The result of the study shows that simple changes based on proper system identification can considerably improve the stability of the machine tool structure.

Partition-based 3 + 2-axis tool path generation for freeform surface machining using a non-spherical tool

Hao Jiancheng,Li Zhaoyu,Li Xiangyu,Xie Fubao,He Dong,Tang Kai 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.5

When machining a complex freeform part, using a non-spherical tool could significantly improve the machining efficiency, as one can adaptively adjust the tool posture to maximize its contact area with the part surface. However, since adjusting the tool posture requires changing the tool orientation, a five-axis machine tool is needed, which is extremely expensive as compared to a conventional three-axis machine tool. Moreover, for a complex freeform surface with high curvature variation, to match its curvature change, the tool axis has to drastically change accordingly, thus inducing high velocity and acceleration on the machine tool’s rotary axes. To address these issues, in this paper we propose a partition-based 3 + 2-axis strategy for machining a general complex freeform surface with a non-spherical tool. As only a finite small number of distinct tool orientations are needed for 3 + 2-axis machining, an indexed three-axis machine tool suffices, thus relieving the need of an expensive five-axis machine tool. In addition, the much-increased rigidity of the three linear axes of the machine tool will greatly improve the kinematics and dynamics of the machine tool and thus enhance the machining accuracy. Experiments in both computer simulation and physical machining are carried out, whose results confirm that, when compared to using a conventional spherical cutter, by using a non-spherical cutter and adaptively adjusting the contacting tool posture and the feed direction, significant improvement in machining efficiency could be achieved, e.g., more than 50% achieved in our experiments.

병렬기구 공작기계의 이송오차 측정에 관한 연구

고해주(Hai-Ju Ko),황종대(Joung-Dae Hwang),정윤교(Yoon-Gyo Jung),김재실(Chae-sil Kim) 한국기계가공학회 2008 한국기계가공학회 춘추계학술대회 논문집 Vol.2008 No.-

The improvement of the productivity and quality of products were caused by adaptation of machine tool in the industry. Also, it is connected with development of products with multi function and high price, so it leads to industrial growth in the field of machine tool. For high speed of the machine tool, the feeding system is an important function, and technical advance of this feeding system is derived the development of 5 axis machine tool mounted high and multi axis feeding system. Moreover, PKMT(Parallel Kinematic Machine Tool) using robot technology with 5 axis function is developed, and it is becoming the advanced machine tool which space motion is very convenient. But low motion accuracy by multi axis movement in PKMT is a serious problem. So, the development of measurement system for the evaluation of motion accuracy is required. In this study, we are purpose to propose the measurement method about the high speed and multi axis feeding system of machine tool, and to obtain reliability for measuring result.