Efficiency Of Machine Tools Research Articles

Review of recent advances on energy efficiency of machine tools for sustainability

Due to the high power consumption of machine tools in the manufacturing plants, study of the energy efficiency of machine tools has been the urgent need for sustainability. This article is focused on a comprehensive literature review about energy-efficient machine tools, including the analysis of energy loss, the modeling, and evaluating of energy efficiency of machine tools. These techniques are applicable for the design of new machine tools, and the analysis or redesign of the existing machine tools. Furthermore, some limitations and barriers of the previous studies on reducing machine tool energy consumption are discussed and outlined. The significant potential toward improving the energy efficiency of machine tools is presented, and some challenges are identified and summarized.

Classification of metal-cutting machines by energy efficiency

Methods of determining the energy efficiency of machine tools are analyzed, including methods based on the input energy balance, the expenditures in machining, and energy losses in the shaping structure of the machine tool. The energy efficiency may be assessed in terms of the energy ratio of the physical processes within the machine tool. On that basis, metal-cutting machines may be classified by energy efficiency.

Increasing the Resource Efficiency of Machine Tools by Life Cycle Oriented Services

The increasing responsibility of companies for sustainable manufacturing of their products requires a resource-efficient use of a machine tool. Aside from technical measures regarding the machines, life cycle oriented services present a high potential for improving resource efficiency. In order to exploit these potentials systematically, a method to identify and to analyze impacts of services on the resource efficiency of a machine tool is required.In this paper, existing approaches for increasing the resource efficiency of a machine tool are analyzed. Then a framework is presented that enables manufacturers of machine tools to improve the resource efficiency of their machines with different services.

Empirical Study of the Power Efficiency of Various Machining Processes

Machining is one of the most widely used subtractive processes, and many studies have reported methods to improve the quality, productivity, and effectiveness of the process. Moreover, in recent years, energy efficiency has become an increasingly important consideration, largely as a result of new legislation and standardization in response to environmental concerns. However, the analysis of the energy efficiency of machine tools is not straightforward because of the complexity of the components and process. This study compared the power efficiency of various machining processes at different scales. Here, power efficiency is defined as the ratio of the process power to the total power consumption, and it was calculated using experimental results from conventional milling, micro-scale drilling, and brushing. The calculated power efficiency is compared for the processes reported here, as well as with selected published data. We found that the power efficiency varied regardless of machining scales or specific energy consumed, and also can vary widely in terms of the peripheral devices used. Moreover, for the case of laser-assistant machining, the present power efficiency metric decreased as the cutting load decreased. Therefore, it is need to consider the effect of the surrounding environment and effectiveness of machining, and suggestions were shown for the concept of novel power efficiency.

Design of High Frequency Power Oscillator Board Based on Rotary Encoder Control

Accurate and stable high frequency pulse power supply is studied to improve high-speed wedm machine tool's efficiency. Regarding to the shortcomings of traditional digital circuit high frequency oscillator board, we design a high frequency power oscillator board based on rotary encoder control, control accuracy and high- frequency waveform by programming, adjusting the frequency and display. It has six brakes of processing function, it also includes feedback function of emulsification oil. The high frequency will be shutdown and the emulsification oil will be changed if there is too much metal dust in emulsification. It has been proved by practice that high- frequency circuit board is simple and reliable and can greatly increase efficiency of wire cutting.

CNC 기계의 원격 에너지 모니터링을 위한 온라인 시스템 구조

Enhancing energy efficiency of machine tools causes substantial impacts on the manufacturing industries, to cope with the competitive introduction of the total energy management strategies. Real-time energy monitoring is essential to identify energy consumption patterns of the machine tools and correlate them with the energy management strategy. Integrated analysis of machine tool’s operation status and the corresponding energy usage is most important to accurately evaluate the energy efficiency under the various machining process environments. This paper proposes a system architecture to realize the online energy monitoring system and the embedded energy monitoring approach interconnected with the CNC kernel. The shop-floor operation management system is presented to integrate the proposed online energy monitoring approach.

High-Efficient Evaluation Method of the Thermal Deviation Characteristic of Machining Center by All Axes Motions

In order to answer the needs for high accuracy and efficiency of machine tools in recent years, thermal deformation has become an important issue. Therefore many studies for suppressing, estimating and compensating the thermal deformation have been carried out. Moreover, the establishment of accurate and efficient measurement and evaluation method of the thermal deformation is also strongly demanded. In the present study, the method to evaluate independently and efficiently the thermal displacement characteristics due to the linear motion of each axis was considered for machining centers. As a result, we have concluded as followed. (1) We could propose All Axis Motion Test (AAMT) method that can evaluate independently and simultaneously the thermal displacement characteristics due to the movement of the each linear axis. (2) AAMT method can be said to be valid, since the experimental results based on this method agrees well with the test result from the single axis motion test. (3) Significantly high efficiency of the measurement and evaluation of thermal displacement of the machining centers is possible by AAMT method

Sustainable Service System for Machine Tools

Quick and correct service is most important for machine tool users. In order to maintain efficiency of machine tools at customers’ sites, remote maintenance and monitoring system, worldwide spare parts supply system, integration of service parts, education system for service engineers, long-term environmental load reduction are necessary. This paper presents current and future activities of machine tool manufacturers for improving the service system.

Machine tool optimization strategies for ecologic and economic efficiency

Optimization activities in manufacturing must be addressed in the multifaceted context that combines economic, social and environmental goals. Research activities of today not only strive to cope with the legislative pressure of the Directive of the European Parliament on Energy Using Products but also strive for economic advantages for the machine tool user by investigating and applying suitable procedures and methods that help to model, forecast and reduce overall energy consumption. A key issue is the reduction of the amount of resources consumed for the same output and the increased machine tool efficiency with the help of selective methods and a minimum investment. A bottom-up approach to identify potential initial points for optimization is given in the presented research work. This article introduces a methodology for detecting and evaluating reasonable investments for retrofit solutions with different approaches. A technical measurement and optimization approach, depending on the actual circumstances, and an economic approach, that is used to detect optimization potentials with the economic evaluation of selected solutions are proposed in this article.

Energy Reduction of Machine Tools

Machine tools, which are used in factories for long hours and many years, have a great influence on power consumption of the factories. Therefore, reducing machine tool power consumption is one of the important subjects for today’s machine tool manufacturers. In this paper, we will report on our ongoing efforts to improve energy efficiency of machine tools.

An on-line approach for energy efficiency monitoring of machine tools

Machining processes cause measurable impacts on environment due to substantial amounts of energy consumption. Enhancing energy efficiency of machine tools can significantly improve the environmental performance of machining systems. For this reason, an on-line energy efficiency monitoring system is necessary. Most conventional approaches monitored the energy efficiency by directly measuring cutting power with torque sensors or dynamometers. In contrast, we propose a new on-line approach without using any torque sensor or dynamometer which leads to a decreased implementation cost. The energy efficiency monitoring model of this approach is constructed based on an energy consumption model of machine tool. Then the entire machine-tool energy consumption can be divided into two parts, i.e. constant energy consumption and variable energy consumption. The former is measured in advance and stored in database, and the latter is derived from cutting power that can be estimated on-line according to power balance equation and additional load loss function. The additional load loss function can be identified off-line through input power and cutting power of the machine-tool spindle. Several experiments are performed on a CNC machine tool CJK6136 and the results show the effectiveness of the proposed method.

A29 全軸運動によるマシニングセンタの熱変位特性の高能率評価法(OS1 最新工作機械(2))

Thermal deformation in machine tools influences greatly on the machining accuracy. Therefore the importance of evaluation of the thermal deviation in machine tools becomes high. Besides, the demand of effective measurement and evaluation of the thermal deviation is becoming strong, since spending the time for the test of the thermal deformation influences directly on the production efficiency of machine tools. Therefore, in this paper, we devised the method which can evaluate independently the characteristics of thermal deviation caused by the single axis linear motion with the multiple linear motions of all axes. As a result, this method showed the much effectiveness in machining centers.

Integrated methodology for the evaluation of the energy- and cost-effectiveness of machine tools

Sustainable machine tools are characterized by less consumption of energy as well as low costs during their life-cycle. In order to design such machine tools an evaluation of the energy-efficiency and the costs incurred is needed. In contrast to this, up to now there has been no fully developed evaluation method relating to both technical and cost efficiency of machine tools. Thus, the paper presents an integrated approach for the evaluation of machine tools consisting of methodological proposals for the measurement of energy consumption, modeling of energy flows and simulative analysis of the energy saving potentials as well as an energy-oriented life-cycle costing concept. Additionally, braking energy storage systems and reactive power compensation are analyzed. Based on the identified energy saving potentials, it is shown that at present only reactive power compensation is economically profitable under given assumptions.

Thermal issues in machine tools

This paper presents a review of the latest research activities and gives an overview of the state of the art in understanding changes in machine tool performance due to changes in thermal conditions (thermal errors of machine tools). The topics are focused on metal cutting machine tools, especially on turning and milling machines as well as machining centres. The topics of the paper thermal issues in machine tools include measurement of temperatures and displacements, especially displacements at the tool centre point, computations of thermal errors of machine tools, and reduction of thermal errors. Computing the thermal errors of machine tools include both, temperature distribution and displacements. Shortly addressed is also to avoid thermal errors with temperature control, the influence of fluids and a short link to energy efficiency of machine tools. The paper presents the summary of research work in the past and current. Research challenges in order to achieve a thermal stable machine tool are discussed. The paper apprehend itself as an update and not a substitution of two published keynote papers of Bryan et al. [28] in 1990 and Weck et al. [199] in 1995.

Structure principles of energy efficient machine tools

Activities for energy efficiency increase of machine tools and production systems can roughly be divided into direct efficiency increase on components level and efficiency increase by optimised interaction of the components on the respective higher system level. The paper is focused on system level. In the first part, influences on energy consumption in production are structured hierarchically. General aspects of energy efficiency of machine tools and production systems will be discussed. In the second part, selected solution approaches for machine tools will be addressed more in detail, especially mobility and miniaturization as well adaptivity through redundancy.

Analysis of Modality of CK61125 CNC Lathe Spindle Box

CNC lathe spindle box is a key component of the CNC lathe system, and its dynamic characteristics are the main factor affecting the machining accuracy and processing efficiency of machine tools. In this paper, CK61125 CNC lathe spindle box model was established by simplifying its structure. Then modal analysis of the spindle box was done and extended to 6-order modes with the platform of co-simulation environment in ANSYS Workbench, and the natural frequencies and vibration modes for lathe spindle box were obtained. The weak links in the spindle box were found, and the improvement schemes are proposed. Finally the lathe spindle box was improved, the modal analysis of the spindle box was made again, and the results showed that the lathe spindle box dynamic performance was improved. All of these results are beneficial for optimization and re-design of the lathe spindle box so that it has better dynamic performance.

A new tool wear estimation method based on shape mapping in the milling process

In the milling process, tool wear has a great influence on product machining quality, especially for a difficult-to-cut material. In this paper, a new approach based on shape mapping is proposed to acquire tool wear in order to establish an off-line tool wear predicting model for assessing the degree of wear and remaining useful life. The new approach maps tool wear shape into a metal material by milling holes mode after finishing each of the machining experiments. The metal material has low influence on tool wear compared to the experimental material. Thus, a series of mapped holes, which can represent the worn tool information, are formed on the metal material when finishing all milling experiments. These mapped holes on the metal material are analyzed according to all types of milling cutters in order to establish the relationship between the characteristic parameters of these mapped holes and tool wear. According to the established relationship, the characteristic parameters of these mapped holes are measured on the coordinate measure machine. The tool wear of each machining experiment can be obtained from the measured characteristic parameters of these mapped holes. The new tool wear estimation method does not require the stoppage of the machine tool and the removal of the cutter to measure tool wear in the process of conducting tool wear experiments. The new method can increase the machine tool efficiency of tool wear machining experiments and provide an efficient way to acquire tool wear in the process of establishing an off-line tool wear predicting model. In order to verify the new tool wear estimation method, a series of machining experiments were conducted on the five-axis machining center for cemented carbide cutting tool milling stainless steel. Experiments show that the shape mapping strategy of tool wear can allow for an effective assessment of tool wear and indicate good correlation with the expected wear characteristics and easily conduct tool wear experiments.

Simulation of Thermal Deformation for Spindle of Machine Tool

In order to increase the efficiency of machine tools, the development of machine tools is toward higher speed and accuracy. The higher speed of spindle causes more thermal deformation, which reduces the accuracy of machine tools. In this study, finite element method is used to simulate the thermal deformation of spindle caused by the friction loads between spindle and bearings. The bearing load is estimated by the basic load rating from the bearing vendor and the required life of bearing. The simulated results are compared with experimental measurements to verify the analysis model. The result shows that the stabilized temperature of spindle increases as the speed increaser, while the stabilized displacement of spindle slightly increases as the speed increases.

ON NONLINEARITY CONTROL OF CNC FEED DRIVES

A Unified Reconfigurable Open Control Architecture (UROCA) aims at unifying the reconfiguration aspects and managing the interaction amongst the different operating levels of individual machining control systems that are likely to perform in reconfigurable manufacturing systems. The hierarchical control structure of UROCA demands the usage of a supervisory control scheme in order to manage operations of supervisory and servo controllers altogether into a reconfigurable control process. The main function of the supervisory unit is to serve as a switching/reconfiguring logic amongst different available controllers, according to need, in order to maintain motion output within the permitted limits. Due to backlash, efficiency of machine tools will be undesirably turned down causing higher vibrations, lower contouring accuracy, and may draw the whole system into instability region. A Switching control scheme designated to manage the control process where two different controllers with two different control functionalities, acting differently in two vital zones - one of them where the backlash lies, and the other when moving past the backlash - is the main topic of this paper. The proposed switching schemes emphasize a reconfiguration aspect on the control process level for machine tools as perceived, investigated and resolved by the physical and control layers located at the deliberative part of the UROCA architecture.

Models of machine tool efficiency and specific consumed energy

Experiments were carried out for statistic modelling of machine tool efficiency and of specific consumed energy in machining. The machine tool efficiency, specific consumed energy and consumed energy have been determined as functions of different machining parameters. For establishing the relationship between the above parameters, the experimental data were statistically modelled using the Response Surface Methodology. The experimental data were obtained by measuring the working parameters of machine tool and the power consumed by the electric motor, for every experience of the experimental program. These data were used in estimation of the coefficients of the models and in their statistic analysis. As an example, the models of efficiency for a vertical-milling machine and of specific consumed energy for milling of an aluminium alloy on this vertical-milling machine are described, ones illustrated.