Machine Tool System Research Articles

Machine tool systems structural characterization, energy transfer, and evolution analysis of milling Ti6Al4V considering cutting vibration

Machine tool systems structural characterization, energy transfer, and evolution analysis of milling Ti6Al4V considering cutting vibration

Design and Technological Aspects of Integrating Multi-Blade Machining and Surface Hardening on a Single Machine Base

Modern mechanical engineering faces high competition in global markets, which requires manufacturers of process equipment to significantly reduce production costs while ensuring high product quality and maximum productivity. Metalworking occupies a significant part of industrial production and consumes a significant share of the world’s energy and natural resources. Improving the technology of manufacturing parts with an emphasis on more efficient use of metalworking machines is necessary to maintain the competitiveness of the domestic machine tool industry. Hybrid metalworking systems based on the principles of multi-purpose integration eliminate the disadvantages of monotechnologies and increase efficiency by reducing time losses and intermediate operations. The purpose of this work is to develop and implement a hybrid machine tool system and an appropriate combined technology for manufacturing machine parts. Theory and methods. Studies of the possible structural composition and layout of hybrid equipment at integration of mechanical and surface-thermal processes were carried out, taking into account the basic provisions of structural synthesis and componentization of metalworking systems. Theoretical studies were carried out using the basic provisions of system analysis, geometric theory of surface formation, design of metalworking machines, methods of finite elements, and mathematical and computer modeling. The mathematical modeling of thermal fields and structural-phase transformations during HEH HFC was carried out in ANSYS (version 19.1) and SYSWELD (version 2010) software packages using numerical methods of solving differential equations of unsteady heat conduction (Fourier equation), carbon diffusion (2nd Fick’s law) and elastic–plastic behavior of the material. The verification of the modeling results was carried out using in situ experiments employing the following: optical and scanning microscopy; and mechanical and X-ray methods of residual stress determination. Formtracer SV-C4500 profilograph profilometer was used in the study for simultaneous measurement of shape deviations and surface roughness. Surface topography was assessed using a Walter UHL VMM 150 V instrumental microscope. The microhardness of the hardened surface layer of the parts was evaluated on a Wolpert Group 402MVD. Results and discussion. The original methodology of structural and kinematic analysis for pre-design studies of hybrid metalworking equipment is presented. Methodological recommendations for the modernization of multi-purpose metal-cutting machine tool are developed, the implementation of which will make it possible to implement high-energy heating with high-frequency currents (HEH HFC) on a standard machine tool system and provide the formation of knowledge-intensive technological equipment with extended functionality. The innovative moment of this work is the development of hybrid metalworking equipment with numerical control and writing a unique postprocessor to it, which allows to realize all functional possibilities of this machine system and the technology of combined processing as a whole. Special tooling and tools providing all the necessary requirements for the process of surface hardening of HEH HFC were designed and manufactured. The conducted complex of works and approbation of the technology of integrated processing in real conditions in comparison with traditional methods of construction of technological process of parts manufacturing allowed to obtain the following results: increase in the productivity of processing by 1.9 times; exclusion of possibility of scrap occurrence at finishing grinding; reduction in auxiliary and preparatory-tasking time; and reduction in inter-operational parts backlogs.

Vibration Friction Investigation on the NCS of Joints of the CNC Machine Tools Considering Friction Factor

Machine tool vibrations play a significant role in hindering productivity during machining. The growing vibrations accelerate tool wear and chipping, cause a poor wave surface finish, and may damage the spindle bearing. Some research showed that tribological properties such as friction factors can have obvious influences on the topography of rough surfaces and the nonlinear dynamic characteristics of machine tool systems. Therefore, studying the vibration friction dynamic characteristics on the normal contact stiffness (NCS) of joints of CNC machine tools is absolutely necessary for improving the machining accuracy and precision of the whole system. The study results of NCS of joints of the CNC and the friction coefficient are discussed in this paper. The model of NCS based on fractal parameters was obtained. The models of deformations of the rough surfaces and contact surfaces were deduced. The results showed that the NCS based on the calculation method considering the elastic–plastic deformation of the asperity is much higher in precision than the methods considering only elastic or plastic deformation separately. The observations this paper described suggest that in the CNC machine tools system, higher D and G and higher friction coefficients lead to higher normal contact stresses (NCSs).

Vibration characteristics and machining performance of carbon fiber reinforced shaft in poor rigidity machining tool system

Vibration characteristics and machining performance of carbon fiber reinforced shaft in poor rigidity machining tool system

Development of a Two-Parameter Inductive Sensor for use in Digital Program Control Systems for Machine Tools

Development of a Two-Parameter Inductive Sensor for use in Digital Program Control Systems for Machine Tools

A Novel Friction Compensation Method for Machine Tool Drive Systems in Insufficient Lubrication.

Friction is the dominant factor restricting tracking accuracy and machining surface quality in mechanical systems such as machine tool feed-drive. Hence, friction modeling and compensation is an important method in accurate tracking control of CNC machine tools used for welding, 3D printing, and milling, etc. Many static and dynamic friction models have been proposed to compensate for frictional effects to reduce the tracking error in the desired trajectory and to improve the surface quality. However, most of them focus on the friction characteristics of the pre-sliding zone and low-speed sliding regions. These models do not fully describe friction in the case of insufficient lubrication or high acceleration and deceleration in machine tool systems. This paper presents a new nonlinear friction model that includes the typical Coulomb-Viscous friction, a nonlinear periodic harmonic friction term for describing the lead screw property in insufficient lubrication, and a functional component of acceleration for describing the friction lag caused by the acceleration and deceleration of the system. Experiments were conducted to compare the friction compensation performance between the proposed and the conventional friction models. Experimental results indicate that the root mean square and maximum absolute tracking error can be significantly reduced after applying the proposed friction model.

A Novel Contact Stiffness Model for Grinding Joint Surface Based on the Generalized Ubiquitiformal Sierpinski Carpet Theory

A novel analytical model based on the generalized ubiquitiformal Sierpinski carpet is proposed which can more accurately obtain the normal contact stiffness of the grinding joint surface. Firstly, the profile and the distribution of asperities on the grinding surface are characterized. Then, based on the generalized ubiquitiformal Sierpinski carpet, the contact characterization of the grinding joint surface is realized. Secondly, a contact mechanics analysis of the asperities on the grinding surface is carried out. The analytical expressions for contact stiffness in various deformation stages are derived, culminating in the establishment of a comprehensive analytical model for the grinding joint surface. Subsequently, a comparative analysis is conducted between the outcomes of the presented model, the KE model, and experimental data. The findings reveal that, under identical contact pressure conditions, the results obtained from the presented model exhibit a closer alignment with experimental observations compared to the KE model. With an increase in contact pressure, the relative error of the presented model shows a trend of first increasing and then decreasing, while the KE model has a trend of increasing. For the relative error values of the four surfaces under different contact pressures, the maximum relative error of the presented model is 5.44%, while the KE model is 22.99%. The presented model can lay a solid theoretical foundation for the optimization design of high-precision machine tools and provide a scientific theoretical basis for the performance analysis of machine tool systems.

A Novel Temperature Rise Prediction Method of Multi-component Feed System for CNC Machine Tool Based on Multi-source Fusion of Heterogeneous Correlation Information

A Novel Temperature Rise Prediction Method of Multi-component Feed System for CNC Machine Tool Based on Multi-source Fusion of Heterogeneous Correlation Information

Online identification and feed-forward compensation of nonlinear friction in servo system based on RBF neural network model

In this paper, an online identification and compensation method of nonlinear friction based on radial basis function (RBF) neural network model is proposed for the influence of nonlinear friction on machining accuracy in the low speed process of servo feed system of CNC machine tools. First, a three-layer single-input-output RBF neural network model is established for describing the nonlinear friction of servo feeding system. Second, the neural network online learning algorithm is improved based on adaptive gain, which improves the stability and accuracy of the algorithm. Finally, experiments were carried out on a three-axis milling machine to compensate the friction in the servo feed system in real time based on the online identification results. The results show that the method can effectively improve the online identification accuracy and convergence rate, and effectively improved the low-speed performance of the servo feed system.

Geometric contact characteristics of variable hyperbolic circular-arc-tooth-trace cylindrical gear under different machine tool errors and sensitivity analysis for impact factors

Machine tool error is one of the most important research contents in gear transmission error, and contact characteristics are important factors affecting gear transmission performance. The establishment of tooth contact analysis (TCA) model of gear pair plays a guiding role in analyzing contact characteristics of gear pair. Based on the forming principle of variable hyperbolic circular-arc-tooth-trace cylindrical gear (VH-CATT gear), the structure model and coordinate system of VH-CATT gear machine tool are established. Based on the gear meshing conditions, the tooth surface mathematical model of the VH-CATT gear with machine tool error are established, and the TCA model with machine tool error is established. The influence of different machine tool errors on the geometric contact characteristics of the gear pair is analyzed. The results show that the pressure angle error, rotation error in y direction, and rotation error in z direction, translation error in y direction, and rotation error in z direction have a significant impact on the contact characteristics of tooth profile of VH-CATT gear.

Thermal Characteristics of Spindle System Based on the Comprehensive Effect of Multiple Nonlinear Time-Varying Factors

The thermal characteristics of the spindle system for CNC machine tools are influenced by multiple factors which are nonlinear and time-varying. In this paper, a nonlinear time-varying thermal characteristics solving model for the spindle system was established based on the numerical solution method. Through theoretical deduction and data fitting, mathematical models of nonlinear time-varying factors including the friction torque generated by lubricants, convective heat transfer coefficient, and coolant and ambient temperature are constructed. The temperature and displacement of the spindle system at each time step are solved by considering the comprehensive effect of multiple nonlinear time-varying factors. And the actual temperature and axial deformation data of the spindle system are obtained through thermal characteristics detection experiments. By comparing solution results affected by multiple nonlinear time-varying factors and by non time-varying factors with experimental data, it can be concluded that the nonlinear time-varying thermal characteristics model has advantages in reflecting the trend of numerical changes and the accuracy of result solving over a method considering non time-varying factors and the solution values of temperature affected by multiple nonlinear time-varying factors are almost consistent with detection values and the relative errors are all within ±3%. The relative error of axial deformation between the value solved by the model and the detection value is close to −1%. This conclusion demonstrates the rationality and accuracy of the thermal characteristics solving model and the construction of nonlinear time-varying factors. This study is of great significance for exploring the thermal characteristics of the spindle system and improving CNC machine tool performance in depth.

Research on thermal characteristics modeling for feed system of CNC machine tool considering thermal parameter correction

Feed system is an essential part of machine tools for controlling cutting. The thermal characteristics of the feed system has a significant impact on the machining accuracy for machine tool. To predict the temperature distribution of the feed system accurately, a dynamic thermal analytical approach for feed system is proposed in this paper, which considers the dynamic change process of the bearing and nut heat source affected by thermal deformation. Taking the feed system of machine tool as the research object, the heat source calculation method and stress modeling process considering the influence of thermal deformation is proposed. The thermal-structural coupling analysis of the feed system and the corresponding experimental data are presented. With the comparison of the simulation and test results, it is concluded that the simulation result of the feed system thermal characteristics analysis is in good agreement with the experimental data, and the established model and method can effectively improve the simulation accuracy of the feed system.

Research on thermal error compensation strategy of CNC machine tools based on full working area modeling

Abstract Traditional manufacturing equipment is developing in the direction of precision, intelligence and integration, and the precision requirements of CNC machine tools are getting higher and higher. Compensating and controlling the thermal error of the machine tool is an important part of improving machining accuracy. This paper uses a cuckoo search algorithm to optimize the BP neural network to get the CSBP neural network model and inputs the temperature value of the CNC machine tool into the CSBP model to get the thermal error prediction results. Combined with the thermal error values of each measurement point on the CNC machine table, the B-spline function is used to fit the thermal error prediction model for the entire working area. Finally, the thermal error compensation system of the CNC machine tool has been established. Simulation and empirical studies show that the fitting and prediction accuracy of the model in this paper are better, and the maximum error value of the prediction is reduced by 20.27% compared to the LSTM model. After the application of the thermal compensation system in this paper, the thermal error of the CNC machine tool is greatly reduced, and most of the offset caused by the thermal deformation of the machine tool is eliminated through compensation. In this paper, the design of a thermal error compensation system based on full work area modeling can effectively reduce the thermal error of CNC machine tools, which can be applied to the actual machining process of machine tools to improve the machining accuracy of CNC machine tools.

Research on Fault Diagnosis Method of Bearings in the Spindle System for CNC Machine Tools Based on DRSN-Transformer

Research on Fault Diagnosis Method of Bearings in the Spindle System for CNC Machine Tools Based on DRSN-Transformer

CNC Machine Tool Focused Edge Computing in Manufacturing

This paper presents a method for standardized integration of external sensors and actuators into CNC machine tool systems utilizing edge computing technology. Different communication protocols and various means for triggering external devices at a chosen machining operation were studied and evaluated using a sensory tool holder. The benefits of the presented architecture are the independence of the host operating system, easy customization, lightweight architecture, and standard protocols. Focusing on the demands for modern edge devices led to containerized modules with customizable interfaces. During manufacturing processes, the system was evaluated in terms of performance and reliability.

Optimised LightGBM-based health condition evaluation method for the functional components in CNC machine tools under strong noise background

Abstract The accurate health condition evaluation of the functional components in computer numerical control (CNC) machine tools is an important prerequisite for predictive maintenance and fault warning. The vibration signals of the functional components in CNC machine tools often contain substantial noise, impeding the extraction of relevant health condition information from the vibration signals. This work presents an approach that leverages the variational mode decomposition (VMD) enhanced by the Artificial Hummingbird Algorithm (AHA) alongside the Light Gradient Boosting Machine (LightGBM) optimised through particle swarm optimisation (PSO) to evaluate the health condition of the functional components in CNC machine tools amidst pervasive noise. Initially, the AHA optimised the penalty factor (α) and the decomposition layer (K) within the VMD. This optimised VMD was subsequently applied to denoise the original vibration signals. After this denoising process, PSO was employed to optimise the learning rate and maximum tree depth within LightGBM. Health condition evaluation experiments were executed on the feed system and spindle of the CNC machine tool to validate the proposed methodology. Comparative analysis indicates that the proposed method attains paramount accuracy and computational efficiency, which are crucial for accurately evaluating the health condition of the functional components in CNC machine tools.

SPECIAL EFFECTS USED IN CREATING 3D ANIMATED SCENES PART II

Today, the computers have made special effects so real, very hard to distinguish from the real elements on the screen, that we can barely notice them. The 3D animation technology development mirrors the progress of technology in the 20th century from mechanization and industrial to computerization and virtual. While the special 3D animation from today could not exist without computers, people are still the ones who conceive these effects. There are many opinions according to which 3D animation will have a much greater impact than it has had up to now. Filming animated 3D scenes offers various opportunities for achieving direct camera shooting. 3D Graphics is a lot more complex, it works with textures, volumes, light schemes and everything is being realized with the help of the computer and of the intelligent mind of the 3D graphics editor. Also, the computer-aided design, the integrated machine-tool systems with automatic control, industrial robots, etc., are some of the current mutations of industrial production that strongly influence product design. The 3D programs are spectacular; thanks to the developments from the hard and software technology, lighting and dynamic renderings specific to 3D scenes can be integrated more and more easily even in complex scenes. The viewer will not even notice that some of the nature landscapes will be generated by the 3D graphic editor. The aim of this article is to briefly present the geometric modelling of some component elements of the proposed 3D scene. Like any other developed product, it has to replace one that already exists, and for it to be accomplished an essential criterion is to introduce a new user facility or to improve the technical performance of the predecessor. Competition also led to diversity, the producers had to capture unexplored market sectors and bring improvements specific to a certain job. The aesthetic valences are ensured by the use of high-quality plastic, metal and ceramic materials and finishing, but also by an arrangement of different primary or combined geometric shapes that confer the status of a “decor” object, when we look at the design of new products as an art.

THE CURRENT STATE OF BLADE MACHINING WITH BLOCK-MODULAR TOOLS ON HEAVY-DUTY CNC MACHINES

The article analyzes the current state of the problem of blade machining, considers ways to improve the efficiency of the machining process on heavy unique machine tools, prefabricated tool systems, tool reliability, evaluates methods for ensuring satisfactory chip formation and their technological capabilities, considers methods of multicriteria optimization, identifies areas of scientific research, and formulates the purpose and objectives of the study. For the first time, the scientific principles of creating block-modular tooling systems for heavy machine tools were published, which include: principles of creating block-modular tooling systems based on qualimetric assessment of the states of the machining process, possible failures of the technological system, properties and criteria for their optimization, determination of the criteria weights; principles of designing block-modular tool elements taking into account the assessment of the stress-strain state and stiffness of the main components, creation of a mathematical model.

Рационализация режимов поверхностной закалки ВЭН ТВЧ рабочих поверхностей пуансона в условиях гибридной обработки

Introduction. The development of a cluster of hybrid metalworking systems in the machine tool industry is associated with a number of positive consequences. First, such systems help reduce production costs by optimizing the use of resources and energy. This is especially true in the face of increased competition and a trend towards savings. Secondly, hybrid systems enable the production of quality products with increased efficiency. By integrating various functions in one process equipment, metalworking processes become more efficient and precise. This reduces the amount of defective products and improves the quality of the final ones. In addition, hybrid metalworking systems have autonomous functionality, which is especially important in flexible engineering production, where rapid changeover and adaptation to various production tasks is required. Thus, hybrid metalworking systems represent an important step in the development of modern mechanical engineering, helping to reduce costs, increase efficiency and ensure high product quality. The purpose of this work is to increase efficiency and reduce energy consumption during surface-thermal hardening of machine parts through the use of concentrated energy sources under integral processing conditions. Theory and Methods. To achieve this purpose, studies were carried out on the possible structural composition and layout of hybrid equipment integrating mechanical and surface-thermal processes. When developing the theory and methods, the main provisions of the structural synthesis and components of metalworking systems were taken into account. Theoretical research is based on the application of system analysis, geometric theory of surface formation and design of metalworking machines. The experiments were carried out on a modernized multi-purpose machining center MS 032.06, equipped with an additional energy source, which was a microwave thyristor-type generator SHF-10 with an operating frequency of 440 kHz, which implements high-energy heating by high-frequency currents. Structural studies were carried out using optical and scanning microscopy. The stress-strain state of the surface layer of the part was evaluated by mechanical and X-ray methods for determining residual stresses. The microhardness of the hardened surface layer of the parts was evaluated on a Wolpert Group 402MVD instrument. Results and discussion. An original method for conducting structural-kinematic analysis for pre-project studies of hybrid metalworking equipment is presented. Methodological recommendations were developed for the modernization of metal-cutting machine tools, allowing high-energy heating with high-frequency currents (HEH HFC) on a standard machine tool system and creating high-tech technological equipment with enhanced functionality. It has been experimentally confirmed that the introduction of the proposed hybrid machine into production in combination with recommendations for the appointment of high-frequency electric power units for integral processing of punch-type parts allows increasing the productivity of surface hardening by 36–40 times and reducing energy costs by 6 times.

FPGA-Based Optimization of Industrial Numerical Machine Tool Servo Drives

This paper presents an analysis of the advantages stemming from the application of field-programmable gate arrays (FPGAs) in servo drives used within the control systems of industrial numerical machine tools. The method of improving the control system that allows for increasing the precision of machining, as well as incorporating new functionalities and streamlining diagnostic processes, is described. As demonstrated, the utilization of digital controllers with robust computational power and high-performance real-time communication interfaces is essential for achieving these objectives. This study underscores the limitations of commonly employed digital controllers in servo drives, which are constructed based on microcontrollers or signal processors collaborating with application-specific integrated circuits (ASICs). In contrast, the proposed FPGA-based solution offers substantial computational power and significantly reduced latencies in the real-time communication interface compared to other examined alternatives. This enables the realization of the planned objectives, specifically the enhancement of technical parameters and diagnostic capabilities of machine tools. Furthermore, the research indicates that FPGA-based digital controllers exhibit relatively low power consumption and a simplified design of the electronic printed circuit board in comparison to other analyzed digital platforms. These features can contribute to heightened reliability and diminished production costs of such controllers. Additional conclusions drawn from the study indicate that FPGA-based controllers provide greater developmental possibilities and their production is marked by potential resilience to challenges associated with the availability of electronic components in the market.