Research on modal analysis method of CNC machine tool based on operational impact excitation

Estimation and analysis of energy consumption for machine tool is the basis of energy efficiency improvement. The existing researches of energy model focus on the static modelling of energy consumption, and a few study of dynamic energy consumption model focus on the dynamic characteristics of operating states of machine tool, the study of dynamic characteristics of energy sources, especially multi energy sources of a CNC machine tool is scarce. Based on the characteristics of CNC machine tool(e.g. multi-energy sources, dynamically changed machining tasks and process parameters), a method for modeling the dynamic energy characteristics of multi-energy sources in CNC machine tool is proposed. The dynamic characteristics of energy consumption process of machine tool are analyzed. On this basis, the colored timed object-oriented Petri net(CTOPN) integrated with virtual component method is applied to model the dynamic energy consumption of machine tool. The CTOPN model is used to describe the dynamic characteristics of operating states of machine tool and multi-energy sources. The virtual component method is used to describe the dynamic characteristics of multi energy sources which is influenced by process parameters. The virtual component model is driven by the information of activity transitions in CTOPN model. The case study shows that the proposed energy model is effective and can provide fundamental support for dynamic energy consumption forecasting, comprehensive depiction of the energy profile and quantitative analysis of influencing factors and so on during the operation of a CNC machine tool, which has significance in practice.

El mecanizado a alta velocidad (MAV) exige nuevos conceptos y estrategias de diseño mecánico de los elementos de las máquinas herramienta, así como el rediseño de todos los aspectos relacionados con los sistemas de control, desde los accionamientos hasta el CNC (integración de sensores, procesamiento y filtrado de señales, algoritmos de control de posición, velocidad y trayectoria), con vistas a obtener prestaciones superiores. En este trabajo se ofrece un estado del arte, con algunos de los hitos más importantes en el área del control aplicado al proceso de mecanizado a alta velocidad. Así, se intentan resumir algunas de las prestaciones más importantes de los nuevos sistemas de control y proponer hacia donde se deben dirigir los esfuerzos principales en los años venideros. Se hace énfasis en los accionamientos lineales y en sus características, que lo convierten en ideal para el MAV. De igual modo, y como aspecto novedoso, se proponen algunos esquemas de control borroso que han tenido éxito en la regulación de procesos no lineales y complejos y que pueden encontrar aplicación en los nuevos servosistemas, estrategias de compensación térmica, sistemas de regulación del fluido de corte y sistemas para optimizar la tasa de arranque de virutas, sólo por citar algunos ejemplos. De esta manera, no sólo es posible aumentar la productividad sino también mejorar el funcionamiento de la máquina herramienta en su conjunto. Por otra parte, se hacen una serie de propuestas de campos abiertos para desarrollos futuros, partiendo del estudio de los logros alcanzados por algunos fabricantes en el diseño de máquinas-herramienta y CNC. Finalmente, se destacan las características de los controladores jerárquicos y algunas de las prestaciones que se pueden alcanzar sin necesidad de grandes modificaciones tecnológicas en la máquina herramienta y considerando un mercado cada vez más dominado por los CNC abiertos.

The static and dynamic performances of a machine tool structure are considered to constitute the primary factors affecting the load-carrying capacity, geometric accuracy and surface precision of the workpiece. The machining performance of a large machine tool under stable conditions is effectively determined by its dynamic response to the cutting force at low-frequency excitation. This study, therefore, investigated the static and dynamic characteristics of a large heavy-duty lathe machine tool in which the headstock and tailstock comprised critical component modules supporting a large workpiece during low-speed machining. Using a finite element model, the influences of the structural modules on the static and dynamic characteristics of the lathe were analyzed, considering the effects of the workpiece load. The results indicated that the fundamental vibration modes of the lathe were primarily dominated by headstock, tailstock, and workpiece behaviors. The maximum compliances of the lathe under the rated load were found to occur at relatively low frequencies (22, 40.7, and 82.7 Hz) and increase with the reduction in workpiece weight. Notably, these modal frequencies were significantly higher than the maximum rotational speed of the spindle (450 rpm). In addition, the dynamic rigidity corresponding to the rated speed was higher than that induced at the natural frequency. These results indicate that the subject lathe possesses sufficient capacity to sustain the cutting load during stable turning machining. This study can, therefore, help designers improve the performance of machine tools for future fabrication.

Purpose: This paper presents a multi-criteria assessment methodology to evaluate the remanufacturability of converting conventional surface grinding machines into CNC machine tools. Methodology: Conventional surface grinding machines remanufactured into CNC machine tools were analyzed and classified into five remanufacturing alternatives. A multi-criteria assessment model incorporating cost, time, accuracy, reliability, processing shape complexity, and ergonomics was developed. The importance of criteria and performance of alternatives were weighted through machine tool remanufacturing experience analysis and comparative literature review. Results: The Remanufacturability Index (RI) for remanufactured conventional surface grinding machines ranges from 0.637 to 0.999 based on the level of CNC upgrades from 2-axis to 5-axis configurations. Higher-axis remanufactured machines showed greater feasibility. Theoretical Contribution: This study provides a quantitative methodology to assess the technical, economic, and environmental feasibility of remanufacturing conventional machines into CNC machine tools. It extends the application of multi-criteria decision making to the field of machine tool remanufacturing. Practical Implications: The proposed methodology can guide small and medium-sized manufacturers in making decisions to upgrade their conventional machines to CNC through remanufacturing. It helps evaluate the benefits and risks of different upgrade configurations to support the implementation of machine tool remanufacturing in practice. Sustainable Development Goals (SDGs): SDG 9: Industry, Innovation and Infrastructure; SDG 12: Responsible Consumption and Production; SDG 8: Decent Work and Economic Growth; SDG 13: Climate Action; SDG 4: Quality Education

This study tackles the crucial problem of low dependability in CNC machine tools made in the country, which frequently have a mean time between failures (MTBF) much shorter than those made in other countries. To address this issue, we provide an enhanced reliability allocation model that considers the connection between subsystems and is based on the conventional Arlins technique. Using 543 connected fault records, our research thoroughly examines fault data from several CNC machine tools in China. We use maximum likelihood estimation to determine correlation coe cients and the Gumbel Copula function to quantitatively characterize the dependency between subsystems. To further improve the model’s exibility in real-world situations, we also add correction factors to modify the failure rates of each subsystem. The findings show that our modi ed model’s more precise distribution of reliability factors among the subsystems improves the overall reliability performance of the CNC machine tools. This study lays the groundwork for future research to examine more in influencing aspects in complex systems and provides a workable answer to the dependability issues experienced by local manufacturers.

With the improvement of CNC technology, CNC machine tools are gradually moving towards high speed, high precision and multi-function. Due to the comprehensive effect of internal and external heat sources, the thermal deformation of the motorized spindle has become the main factor affecting the machining accuracy of the machine tool in high-speed machining. ANSYS software is a large-scale general-purpose finite element analysis software integrating structure, fluid, electric field, magnetic field, and sound field analysis. It can interface with most CAD software, realize data sharing and exchange, and can effectively analyze the temperature and thermal changes of CNC machine tools. Therefore, this paper analyses the thermal deformation mechanism of the spindle of CNC machine tools in computer software, to provide the basis for reducing the thermal deformation of the motorized spindle of CNC machine tools in the future.

With rapid industrial upgrading along the global value chain of manufactured goods, China has transformed, within one generation, from an impoverished agrarian society to a middle-income nation, as well as the largest manufacturing powerhouse in the world. This article identifies the pattern of China's industrial upgrading and compares it with those of other successfully industrialized economies and with the failed ones. We find that (i) China (since 1978) followed essentially the same path of industrial upgrading as that of Japan and the "Asian tigers." These economies succeeded in catching up with the developed western world by going through three developmental stages sequentially; namely, a proto-industrialization in the rural areas, a first industrial revolution featuring mass production of labor-intensive light consumer goods, and then a second industrial revolution featuring mass production of the means of mass production (i.e., capital-intensive heavy industrial goods such as steel, machine tools, electronics, automobiles, energy, communication and transport equipment). (ii) In contrast, economies stuck in the low-income trap or middle-income trap did not follow the above sequential stages of industrialization. For example, many Eastern European and Latin American countries after WWII jumped to the stage of heavy industrialization without fully developing their labor-intensive light industries and, thus, stagnated in the middle-income trap. Also, there is a clear lack of proto-industrialization in the rural areas for many African economies that have remained in the low-income trap. We believe that laissez-faire and "free market" alone is unable to trigger industrial upgrading. Instead, correct government-led bottom-up industrial policies are the key to escaping the low-and middle-income traps.

With rapid industrial upgrading along the global value chain of manufactured goods, China has transformed, within one generation, from an impoverished agrarian society to a middle-income nation as well as the largest manufacturing powerhouse in the world. This article identifies the pattern of China?s industrial upgrading and compares it with those of other successfully industrialized economies and the failed ones. We find that (i) China (since 1978) followed essentially the same path of industrial upgrading as that of Japan and the ?Asian Tigers.? These economies succeeded in catching up with the developed western world by going through three developmental stages sequentially; namely, a proto-industrialization in the rural areas, a first industrial revolution featuring mass production of labor-intensive light consumer goods, and then a second industrial revolution featuring mass production of the means of mass production (i.e., capital-intensive heavy industrial good s such as steel, machine tools, electronics, automobiles, communication and transport infrastructures). (ii) In contrast, economies stuck in the low-income trap or middle-income trap did not follow the above sequential stages of industrialization. For example, many Eastern European and Latin American countries after WWII jumped to the stage of heavy industrialization without fully developing their labor-intensive light industries, and thus stagnated in the middle-income trap. Also, there is a clear lack of proto-industrialization in the rural areas for many African economies that have remained in the low-income trap. We believe that laissez-faire and ?free market? alone is unable to trigger industrial upgrading. Instead, correct government-led bottom-up industrial policies are the key to escaping the low- and middle-income traps.

Increasing the productivity of high-precision manufacturing requires efficient product inspection, for example, using integrated scanning systems on CNC machine tools (MT). However, measuring the dimensional and shape accuracy of workpieces using a touch probe (TP) on MT is negatively affected by the geometric accuracy setting of the MT, thermal stability of the MT and its surroundings, type of scanning system.The aim of this paper was to examine the possibilities of assessing the capability of touch probe measurements on MT, to define the size of the permissible controlled tolerance of the workpiece and to assess the influence of the geometric accuracy of the machine on the size of the permissible tolerance parameter of the inspected workpiece. In the presented experiments, the calculation of the TP measurement capability is based on a new approach respecting the VDA5 standard extended by the minimum tolerance (TOLmin) conformity assessment procedure according to ISO 14253-1:2017.

To cope with the increasingly competitive and demanding markets, CNC machine tool company needs a new form of development that focuses on two core competency factors: ‘process’ and ‘knowledge’. This study presents a knowledge-centric process management framework for the CNC machine tool design and development (D&D) with the integration of process and knowledge. Requirements for the framework are generated based primarily on the nature of the machine tool design practice. The proposed framework consists of process integration model, process simulation, process execution and knowledge objects management modules. Each of these modules is elaborated to support the knowledge-centric machine tool development process management. Finally, the prototype development is presented. Results of this study facilitate the knowledge integration in CNC machine tool D&D, and thus increase machine tool development capability, reduce development cycle time and cost, and ultimately speed up the effectiveness and ensure the excellent machine tool development.

High-speed and high-accuracy machining have become indispensable requirements in modern manufacturing, particularly with the widespread use of computer numerical control (CNC) machine tools in precision engineering applications. However, one of the key challenges in achieving high machining accuracy is the deviation between the programmed feedrate and the actual feedrate during operation, caused by the acceleration and deceleration (Acc/Dec) behavior of the machine tool's servo control system. These discrepancies lead to deviations in the toolpath, which in turn reduce the dimensional accuracy and surface quality of the machined components. Compounding this issue, the cutting forces acting on the tool during high-speed milling operations—especially with square-end mills—cause elastic deflection of the tool, further compromising the geometric precision of the final product. To address these challenges, this study proposes an integrated methodology that combines modeling of actual feedrate variation with predictive estimation of cutting force and tool deflection. The feedrate model is developed by considering the Acc/Dec characteristics of the control axes in the machine tool, enabling accurate prediction of real tool movements. Simultaneously, a cutting force model is constructed based on machining parameters and tool geometry to estimate the magnitude of tool deflection. By integrating both models, the proposed approach allows for the accurate prediction of the actual toolpath and compensation for deviations arising from control limitations and mechanical deflection. The effectiveness of this method was validated through machining experiments conducted without high-precision contour control. The results demonstrated a strong correlation between predicted and measured toolpaths, confirming the reliability and practicality of the proposed method. This study highlights the importance of accounting for dynamic feedrate behavior and cutting mechanics in improving machining accuracy, offering a valuable solution for enhancing dimensional control in high-speed CNC milling applications.

Lightweight heavy-duty CNC horizontal lathe based on particle damping materials

The CNC Machine Tools with high efficiency, high precision and high stability is the inevitable trend of the modern manufacturing industry development.This development trend puts forward the extremely high request to the CNC machine tool error compensation technology. However, the error of CNC machine tools have a variety of reasons, these errors affect each other, which leads to the inevitable error. At the high efficiency processing, we must ensure the high stability and high precision of the machine tool. Which requires the error compensation function to maintain high stability and high compensation accuracy, when the CNC machine tool is under the action of high speed and dynamic load. The rapid development of computer technology provides us with more possibilities to solve error compensation. CNC machine tool error compensation technology based on computer is an important means to improve the machining accuracy in the manufacturing industry, which reduce the error in the production process and increase the production efficiency. This paper firstly analysis the error classification and error source percentage of CNC machine tools. And then it analysis the movement error when the CNC machine tools is working. Finally, it puts forward the key technique and application of error compensation based on computer.

In the process of thermal error modeling of machine tools, the error information is not transparent and the data characteristics are not comprehensive. The Dijkstra algorithm provides an optimization for the classical algorithm, and improving the accuracy of machine tools is an important issue in advanced manufacturing technologies. In this paper we study two methods of error avoidance and error compensation. For CNC machine tools, computer real-time error compensation technology is an economical and effective basic approach. The application of the folded Dijkstra algorithm to realize the compensation technology of the full error model of geometrical machine tool including geometric error and thermal error is put forward. The practical results show the geometric error and thermal error are compensated on 3-axis and 4-axis CNC machine tools, and the accuracy of the error model and the practicality of the compensation method.

With the continuous development and application of digital technology, CNC machine tools have become the main production equipment in the manufacturing industry. CNC machine tools are developed on the basis of the theory of CNC technology, but it is necessary to design the system with some computer-aided design to achieve automatic management. This paper analyzes the computer aided technology and numerical control technology applied in the numerical control machine tool error analysis of the practical application of, and by using multiple regression analysis method for the computation of the efficiency and quality of application of computer aided technology and numerical control technology of CNC machine tool error analysis on the efficiency and quality of data with 15% and 45% respectively than traditional CNC machine analysis, proves that computer aided technology and numerical control technology for numerical control machine tool error analysis plays an important role.