CNC System Research Articles

Analysis of existing means of the cutting tool path visualization in the CNC systems

BACKGROUND: Currently, machines for processing metals and other materials are used in various industry sectors. Operation of these machines defined with the CNC is impossible without using the corresponding systems, which ensure performing real-time configuring of the system for solving various technological tasks by means of machine drives control. AIM: Analysis of functional capabilities of the visualization module of the AksiOMA Kontrol CNC system in comparison with other well-known same-type systems with consequent enlarging of capabilities of this module. Based on this, the study aim is formulated as follows: broadening the functional capabilities of the module of cutting tool motion path visualization in the AksiOMA Kontrol CNC system by means of development of the path analysis module. METHODS: For achieving the aim, the next task to broaden the functional capabilities of the module of cutting tool path visualization in the AksiOMA Kontrol CNC system is formulated as follows: analysis of existing means of cutting tool path visualization in the CNC systems. RESULTS: The study result is the fact that the visualization interface is critically important for operation, as it helps the operator to assess the abnormal situation quickly. Mistakes can be found at every stage of part machining setting-up. The mistakes can be made when positioning the part or the tool, at zero-point binding, at axes offset setting-up, etc. When machine equipment is set up, generally, difficulties take place if there is a different set-up for the other order. For these cases, in the CNC systems, such functional capabilities as processing visualization are necessary. This functionality is critically important, as it helps to find a mistake in time, to assess the danger level, and to fix it in time, that helps to prevent both the machine and the tool from failure and excessive mechanical impact. CONCLUSION: The study, which contains solving the tasks of analysis of cutting tool motion path in the AksiOMA Kontrol CNC system, is completed. The analysis conducted in the paper revealed that majority of CNC systems does not have the presented functional capabilities that does not help to conduct the complete analysis of the machining process.

Hierarchical Control in Mechatronic Technological Systems

The topic of hierarchical control of technological machines is one of the most relevant in mechanical engineering technology. The most difficult issue in this area is the organization of interactions between different control levels, on the one hand, and the choice of automatic control methods for each of these control levels (control by deviation, control by disturbance, mixed control, etc.), on the other. In this article, in relation to machining technology, a method and corresponding device are proposed that make it possible to implement the control of cutting force parameters (axial cutting force and cutting torque) in an automatic control system for the deviation of cutting torque by changing the axial cutting force (lower level of control). The lower-level control ensures the required quality of the surface layer (surface integrity) of the machined parts. At the same time, the required dimensional accuracy of parts is ensured at the upper level of control, which is implemented by the CNC system of the machine. At the upper level, automatic control is carried out based on the deviation of the kinematic parameters of the movement of the working parts of the CNC machine (acceleration, speed, displacement). Control switching from upper to lower level and back is carried out without using a spindle linear axial movement sensor. Instead of this expensive sensor, a limit switch (a closed and opened pair of contacts) is used, which fixes the lowest axial position of the spindle (and cutting tool). Based on the signal of closing the specified contacts of the limit switch, a transition from the lower control level to the upper one is carried out. Thus, the upper-level system operates only when these contacts are closed, and the lower-level system operates only when they are open. In relation to the upper-level system, the lower-level control system implements the control “by disturbance” principle, also known in control theory as the “disturbance compensation principle”.

An Agent-Based Method for Feature Recognition and Path Optimization of Computer Numerical Control Machining Trajectories.

In recent years, artificial intelligence technology has seen increasingly widespread application in the field of intelligent manufacturing, particularly with deep learning offering novel methods for recognizing geometric shapes with specific features. In traditional CNC machining, computer-aided manufacturing (CAM) typically generates G-code for specific machine tools based on existing models. However, the tool paths for most CNC machines consist of a series of collinear motion commands (G01), which often result in discontinuities in the curvature of adjacent tool paths, leading to machining defects. To address these issues, this paper proposes a method for CNC system machining trajectory feature recognition and path optimization based on intelligent agents. This method employs intelligent agents to construct models and analyze the key geometric information in the G-code generated during CNC machining, and it uses the MCRL deep learning model incorporating linear attention mechanisms and multiple neural networks for recognition and classification. Path optimization is then carried out using mean filtering, Bézier curve fitting, and an improved novel adaptive coati optimization algorithm (NACOA) according to the degree of unsmoothness of the path. The effectiveness of the proposed method is validated through the optimization of process files for gear models, pentagram bosses, and maple leaf models. The research results indicate that the CNC system machining trajectory feature recognition and path optimization method based on intelligent agents can significantly enhance the smoothness of CNC machining paths and reduce machining defects, offering substantial application value.

Влияние динамических характеристик процесса резания на шероховатость поверхности детали при токарной обработке

Introduction. The formation of the surface of a part when processing it on a metal-cutting machine is based on properly selected cutting modes. Complex methods of ensuring the specified quality of the part surface also take into account the tool geometry, its condition, and include corrections for tool deviation from the trajectory set by the CNC system under the influence of kinematic disturbances and spindle wavering. Subject. The paper analyzes the relationship between cutting modes and dynamic characteristics of the turning process, and its mapping into surface roughness. The aim of the work is to evaluate the influence of technological cutting modes taking into account the vibration activity of the tool on the roughness of the machined surface by means of simulation modeling. Method and methodology. Mathematical simulation of the dynamics of the cutting process is given, on the basis of which a digital simulation model is built. A methodology of using the simulation model for determining optimal cutting modes and predicting surface roughness taking into account tool vibrations is proposed. By means of experiments and analysis of the frequency characteristics of tool vibrations, the created model is validated, parameters of the cutting forces model subsystem and dynamic tool subsystem are specified, and geometrical topologies of the part surface are constructed. The calculated cutting forces are compared with experimental forces, and similar patterns and levels of characteristics are observed. An assessment of the optimality of the selected cutting modes is proposed based on the analysis of the tool vibration spectrum relative to the workpiece and the results of the numerical model simulation. Results and Discussion. A comparison of the results of digital modeling of the geometrical surface of the workpiece and the real surface obtained during the field experiment is given. It is shown that the roughness of the real surface obtained by machining with constant cutting modes varies relative to the surface roughness of the simulation model within the limits of not more than 0.066 µm.

Research and Development of an Embedded Multi-Channel Sensor Data Acquisition Device for Reservoir Dams

The embedded system of intelligent reservoir dam achieves the integration and efficient utilization of water conservancy dam system data through multi-channel data collection and analysis calculated by computer technology, CNC system, and neural network. Compared with traditional data collection and processing methods, both timeliness and accuracy have been greatly improved. This study aims to develop a multi-channel sensor data acquisition device for reservoir dams based on embedded system technology. This device can collect real-time and efficient data from sensors in various parts of the dam, ensuring the safe operation of the reservoir dam. By using advanced embedded system technology, this device has advantages such as low power consumption, high stability, and real-time data transmission. The Analytic Hierarchy Process (AHP) was used to study the embedded multi-channel sensor data acquisition device for reservoir dams in multiple directions and factors. The AHP method provides an effective means for problem decision-making in complex situations. Referring to the AHP method, the factors that affect reservoir dams can be divided into different levels. Compare the importance of two random factors in each level to obtain a specific quantitative expression of the relative important factors on a scale. Then repeat this step to obtain the weight ranking for different levels. At the same time, the device monitors key parameters such as temperature, humidity, displacement, and pressure in various parts of the dam through multiple sensors, providing strong support for early warning and decision-making of reservoir dams. The results of this study have important practical significance and application value for improving the safety and stability of reservoir dams.

Interactions of NaCl with cellulose I$$\beta$$ crystal surfaces and the effect on cellulose hydration: a molecular dynamics study

AbstractCrystalline nanocellulose is widely used for example, in the paper-making and food industries, as support matrix material or reinforcement of polymer materials, but also in drug carrier and nanomedicine applications. Interestingly, aqueous solutions of cellulose are extremely sensitive to small amounts of added salt yet mere considerations of charge screening leave open questions regarding the mechanisms, especially for unmodified cellulose in aqueous solutions. Here, we map NaCl ion distributions and the effect of added NaCl salt on the hydration of I$$\beta$$ β cellulose nanocrystal (CNC) surfaces by atomistic detail molecular dynamics simulations with explicit water solvent. The simulations reveal the dependency of the hydration layers of the six surfaces of CNCs on the ions, as well as NaCl ion binding sites, and preferences in terms of binding free energy for the ions near CNC surfaces at different NaCl concentrations. We discuss the modelling results against our prior rheology characterization of cellulose solutions. Together, the results indicate that the high sensitivity of cellulose aqueous solutions to added salt rises from the ions near the surface changing locally the ordering and structure of the hydration layers of the CNC surfaces. The revealed mechanism of salt-induced viscosity changes in cellulose aqueous solutions allows advanced design of gelling CNC systems for various end uses and may also guide tuning cellulose interactions by different solvent environments.

Dimensional Characterization and Hybrid Manufacturing of Copper Parts Obtained by Atomic Diffusion Additive Manufacturing, and CNC Machining.

The combination of Atomic Diffusion Additive Manufacturing (ADAM) and traditional CNC machining allows manufacturers to leverage the advantages of both technologies in the production of functional metal parts. This study presents the methodological development of hybrid manufacturing for solid copper parts, initially produced using ADAM technology and subsequently machined using a 5-axis CNC system. The ADAM technology was dimensionally characterized by adapting and manufacturing the seven types of test artifacts standardized by ISO/ASTM 52902:2019. The results showed that slender geometries suffered warpage and detachment during sintering despite complying with the design guidelines. ADAM technology undersizes cylinders and oversizes circular holes and linear lengths. In terms of roughness, the lowest results were obtained for horizontal flat surfaces, while 15° inclined surfaces exhibited the highest roughness due to the stair-stepping effect. The dimensional deviation results for each type of geometry were used to determine the specific and global oversize factors necessary to compensate for major dimensional defects. This also involved generating appropriate over-thicknesses for subsequent CNC machining. The experimental validation of this process, conducted on a validation part, demonstrated final deviations lower than 0.5% with respect to the desired final part, affirming the feasibility of achieving copper parts with a high degree of dimensional accuracy through the hybridization of ADAM and CNC machining technologies.

An Adapted NURBS Interpolator with a Switched Optimized Method of Feed-Rate Scheduling

With the increasing demand for processing precision in the manufacturing industry, feed-rate scheduling is a crucial component in achieving the processing quality of complex surfaces. A smooth feed-rate profile not only guarantees machining quality but also improves machining efficiency. Although the typical offline feed-rate scheduling method possesses good processing efficiency, it may not provide an optimal solution due to the NP-hard problem caused by the feed-rate scheduling of continuous curve segments, which easily results in excess kinetic limitations and feed-rate fluctuations in a real-time interpolation. Instead, the FIR (Finite Impulse Response) method is widely used to realize interpolation in real-time processing. However, the FIR method will filter out a large number of high-frequency signals, leading to a low-processing efficiency. Further, greater acceleration or deceleration is required to ensure the interpolation passes through the segment end at a predefined feed rate and the deceleration in the feed rate profile appears earlier, which allows the interpolation to easily exceed the kinetic limitation. At present, a simple offline or online method cannot realize the global optimization of the feed-rate profile and guarantee the machining efficiency. Moreover, the current feed-rate scheduling that considers both offline and online methods does not consider the situation that the call of offline data and online prediction data will lead to a decrease in the real-time performance of the CNC system. Further, real-time feed-rate scheduling data tend to dominate the whole interpolation process, thus reducing the effect of the offline feed-rate scheduling data. Hence, based on the tool path with C3 continuity (Cubic Continuously Differentiable), this paper first presents a basic interpolation unit relevant to the S-type interpolation feed-rate profile. Then, an offline local smooth strategy is proposed to smooth the feed-rate profile and reduce the exceeding of kinetic limitations and feed-rate fluctuations caused by frequent acceleration and deceleration. Further, a global online smoothing strategy based on the data generated by offline pre-interpolation is presented. What is more, FIR login and logout conditions are proposed to further smooth the feed-rate profile and improve the real-time performance and machining efficiency. The case study validates that the proposed method performs better in kinetic results compared with the typical offline and FIR methods in both the simulation experiment and actual machining experiments. Especially, in actual processing experiments, the proposed method obtains a 28% reduction in contour errors. Further, the proposed method compared with the FIR method obtains a 15% increase in machining efficiency but only a 4% decrease compared with the typical offline method.

ОСОБЕННОСТИ ПОДГОТОВКИ И ПРОВЕДЕНИЯ ЭКСКУРСИЙ В ЕСТЕСТВЕННОНАУЧНОМ МУЗЕЕ И В БОТАНИЧЕСКОМ САДУ

The article talks about the important role played by the rectilinear-directing mechanism in the history of world science and technology. Using the example of pantograph, an early mathematical instrument, we will trace the development of this design, unique in its simplicity, over time and show rare examples of these devices from the collection of the Museum of Bauman Moscow State Technical University. The widespread use of pantographs dates back to the 18th-19th centuries, which allows us to reveal the relationship between natural sciences (the body of knowledge about the Earth, natural objects, phenomena and processes) and engineering, purely technical disciplines, using the example of the use of these scientific instruments in the activities of naturalists and scientists and inventors. Until recently, in mechanical engineering, the use of pantograph mechanisms made it possible to solve the problems of producing parts with complex shaped surfaces on copying machines without the use of CNC systems. Nowadays, copying machines with pantographs continue to be produced, but rather for hobbies, leisure, and artistic processing of materials. The authors’ choice of the topic is dictated by the infrequent mention of such tools and mechanisms in modern Russian publications and sources.

ПАНТОГРАФ: ИСТОРИЯ УНИВЕРСАЛЬНОЙ КОНСТРУКЦИИ

The article talks about the important role played by the rectilinear-directing mechanism in the history of world science and technology. Using the example of pantograph, an early mathematical instrument, we will trace the development of this design, unique in its simplicity, over time and show rare examples of these devices from the collection of the Museum of Bauman Moscow State Technical University. The widespread use of pantographs dates back to the 18th-19th centuries, which allows us to reveal the relationship between natural sciences (the body of knowledge about the Earth, natural objects, phenomena and processes) and engineering, purely technical disciplines, using the example of the use of these scientific instruments in the activities of naturalists and scientists and inventors. Until recently, in mechanical engineering, the use of pantograph mechanisms made it possible to solve the problems of producing parts with complex shaped surfaces on copying machines without the use of CNC systems. Nowadays, copying machines with pantographs continue to be produced, but rather for hobbies, leisure, and artistic processing of materials. The authors’ choice of the topic is dictated by the infrequent mention of such tools and mechanisms in modern Russian publications and sources.

Acceleration and deceleration control algorithm of CNC system based on deep neural network reinforcement learning and MCU

Acceleration and deceleration control, as one of the key technologies in high-speed CNC system, directly affects the machining efficiency, the stability of machining process and the error of machining follow. Therefore, it is necessary to study and explore new acceleration and deceleration control methods in high-speed CNC system to ensure the smooth feed and improve the machining accuracy. Therefore, the acceleration and deceleration control algorithm of NC system based on deep reinforcement learning and single chip microcomputer is studied. The theoretical basis of deep reinforcement learning is analyzed, and the acceleration of acceleration and deceleration is calculated based on the linear acceleration and deceleration control. The whole integer operation of single chip microcomputer is used to estimate the value range of each step. The variation characteristics of trajectory motion are predicted so that acceleration and deceleration can be processed across program segments. The velocity of transfer point is calculated by the rate of change of feed velocity vector, and the speed of multi-program is smoothed by adjusting the allowable contour error. Based on the proximal strategy optimization algorithm in deep reinforcement learning, the acceleration and deceleration control model of CNC system is established to realize the acceleration and deceleration control. The experimental results show that the proposed algorithm has better control effect, shorter time and smaller interpolation error, which can ensure the NC system to feed smoothly at high speed.

Design and implementation of an innovative canned cycle for variable pitch thread cutting on CNC milling machines

This paper presents the development of a new canned cycle for CNC milling machines capable of cutting threads with variable pitch, addressing a significant limitation in modern CNC systems. While existing CNC milling machines provide canned cycles for thread cutting, they lack the capability to program variable pitch, necessitating reliance on CAM systems. In response, the proposed canned cycle offers increased flexibility, quicker setup times, and reduced dependence on CAM systems. The cycle accommodates both internal and external threads, supports left-hand or right-hand threading, and incorporates a user-friendly control panel for easy programming. To validate its efficiency, the canned cycle is implemented using a G-code parametric algorithm, and a series of simulation tests are conducted. The results demonstrate the viability and advantages of the new CNC milling feature in cutting threads with variable pitch, opening up possibilities for various mechanical applications.

A digital solution for CPS-based machining path optimization for CNC systems

A digital solution for CPS-based machining path optimization for CNC systems

Five-axis path smoothing based on sliding convolution windows for CNC machining

Tiny linear toolpaths widely used in five-axis CNC machine tools only meet G0 continuity at the junctions of adjacent paths, the tangential and curvature discontinuities at the corners result in decelerations and fluctuations of machine tools. Although the corner smoothing for the three-axis tool path is relatively mature, the five-axis tool pose path smoothing is still difficult to plan due to the nonlinear motions of the rotational axes and the parameter synchronization between the tool center point (TCP) path and the tool orientation vector (TOV) path. Therefore, this paper aims to extend the smoothing scopes of previously presented mixed tiny path smoothing method based on sliding convolution windows for three-axis CNC machining (Zhang et al. in Journal of Manufacturing Process 102:685–699, [19]). Compared with the previous work, this paper converts the five-axis tool pose path into the tool position signal and tool orientation signal, and the interpolation points of the two path signals in the convolution window are directly processed on the basis of the synchronous motions of all axes. The original parameter synchronization relationship between the TCP path and the TOV path is still maintained. Besides, the smoothing error prediction model is constructed. The proposed five-axis path smoothing method has been integrated into a self-developed open-architecture CNC system and its effectiveness for the five-axis path optimization is validated via the simulation and experiment.

Spherical path planning for multi axis support free additive manufacturing of truss structures

Multi-axis additive manufacturing systems are gaining increasing attention due to their potential for unsupported manufacturing and reduced stair-stepping effects. In response to the challenges of unsupported printing for truss structures, a five-axis path planning method based on spherical slicing has been proposed. Leveraging the implicit expression equation based on cylinders, this study has effectively achieved the generation of efficient surface slicing and five-axis spherical path. The employed path planning method demonstrates significant advantages in both generation efficiency and stability. In the testing experiments, various unsupported path planning schemes are generated for different truss cells and truss structures, including configurations such as the “bridge” and cross-cylinder truss cells. To validate and extend the applicability of this method, two types of five-axis additive manufacturing devices are utilized: one based on a five-axis CNC system and the other employing a UR10 robot. The manufacturing experiments have effectively verified the feasibility of the spherical slicing algorithm in manufacturing various truss unit types, which provides a new technical way for the unsupported manufacturing of truss structures in the future.

Research on the Design and Control Strategy of the Second Simulated Spindle under KND CNC System

Research on the Design and Control Strategy of the Second Simulated Spindle under KND CNC System

Modeling and compensation of enhanced volumetric error of machine tools containing crosstalk errors

The error compensation method is an economical and effective method to improve the machining accuracy of machine tools. Conventional volumetric error modeling of machine tools is based on the rigid body kinematics model using 21 terms of geometric errors and assumes the geometric error of one axis is independent of other axes. However, if the error motion does not satisfy this assumption in serial machine tools, it may significantly influence the overall machine tool accuracy. This paper reveals the existence of mutual crosstalk of angular errors in coupling axes by experiments with equipping the five-degree-of-freedom (5-DOF) embedded sensor module in each axis. A new on-machine measurement method is proposed for detecting crosstalk errors of the coupling axes covering the whole coupling area. It is confirmed that the position-dependent geometric errors (PDGEs) of each axis should be modified by two-dimensional dependence. Therefore, extended from the normal volumetric error model (NVEM) that is commonly used nowadays, a novel enhanced volumetric error model (EVEM) that contains crosstalk's PDGEs is proposed. The real-time error compensation controller (RECC) embedded in CNC system kernel has been developed in collaboration with the vender by writing in the application function. The effectiveness and feasibility of the EVEM and RECC are verified by non-cutting and cutting experiments. Through comparison tests with laser interferometer on body diagonals, the accuracy improving rate of EVEM is about 10 % higher than NVEM. The real-cutting tests on the ISO10791 sample are verified by a CMM and the results show the accuracy improvement of EVEM is better than NVEM by about 20 %.

An optimized data interaction structure for SERCOS-based open CNC system

An optimized data interaction structure for SERCOS-based open CNC system

Analytical method to extract tool workpiece engagement from CAM data for five-axis machining stability prediction

Ball end milling cutters are commonly used for precision machining of complex curved parts in five axis CNC systems. To solve the problem of difficulty in adjusting the spindle speed to achieve stable milling during the five axis milling process of ball end cutters, this paper presents an analytical method for extracting the tool-workpiece engagement (TWE) from computer-aided manufacturing (CAM) data. This method extracts the TWE between the end portion of the ball-end mill and the surface of the workpiece during the processing of free-form surfaces, including slotting, first cutting, and following cutting. Further, the TWE extracted by this method is applied for constructing the cutting force model. The entry and exit angles for each of the micro-element cutting edges under different tool postures are obtained through the conversion matrix, and an efficient full discretization method is used for predicting the stability of the five-axis machining in the slotting mode. Finally, the accuracy and efficiency of the analytical method are verified through simulation and experimentation. The experimental results show that the efficiency of the proposed method increases by about 69% when compared to the arc-surface intersection method and that the predicted value of the five-axis machining stability shows good agreement with the experimental results.

Trusted CNC System Based on the AxiOMA Control Platform

Trusted CNC System Based on the AxiOMA Control Platform