Java Language for Numerical Control Simulation System Research

Java language is widely used in a variety of development platforms to develop all kinds of application software for its simple and efficient.The programming language owning platform independent is adopted to solve the image flicker,sound loading and other issues by the threading technology,multimedia technology,graphics and point by point comparison techniques.Dynamic real⁃time process simulation is implemented and a two⁃dimensional network of CNC machining simulation system is developed while Java applet application is as a carrier.The simulation results show that the system has a friendly interface and fast calculation speed,and platform portability has a certain practicality and application value.

Numerical Controlled Rolling Process of Thick Metal Plate

Thick metal plate rolling process has become more and more important in building a flat roof of drilling on the bottom at sea. This is because not only the product quality requirement higher and higher but also the marketing competition. To improve the process of thick metal plate rolling and to increase productivity a numerical controlled rolling process is developed, which include the process planning, the mathematical model establishment and the numerical control system development. The process is for the 17 000 kN×3 000 mm movable up roller bending machine. According to the machine configuration non-symmetry rolling process is planed. This makes it possible to integrate all the steps of plate shaping up such as end side bending, several times of semi-shape bending and the last shape finishing. Since the process will perform under the numerical controlled condition whole steps of the process are considered can be worked in the automatic cycle. The mathematic model consists of two sections, the theory model and the experience parameters model. Which takes the original plate parameters such as geometry and mechanics, characters of the machine such as the movement limits, tonnage and so on as input and calculates all the parameters needed in process performing. Meanwhile, the mathematic Model is totally adapted to the control system. The numerical control system development scheme is based on all the works above. Here, a system plan is provided. The functional modules and hardware selection, in detail, are introduced. The system software on top level and the controlling software for controller are developed. And some unit techniques in the system such as timer setting, communication between system and controller, video integration, and the ability of resisting impact force are introduced. The process has been used successfully in production for more than two years. Practice approves that the process is robust.

Bayesian zero-failure reliability modeling and assessment method for multiple numerical control(NC) machine tools

A new problem that classical statistical methods are incapable of solving is reliability modeling and assessment when multiple numerical control machine tools(NCMTs) reveal zero failures after a reliability test. Thus, the zero-failure data form and corresponding Bayesian model are developed to solve the zero-failure problem of NCMTs, for which no previous suitable statistical model has been developed. An expert-judgment process that incorporates prior information is presented to solve the difficulty in obtaining reliable prior distributions of Weibull parameters. The equations for the posterior distribution of the parameter vector and the Markov chain Monte Carlo(MCMC) algorithm are derived to solve the difficulty of calculating high-dimensional integration and to obtain parameter estimators. The proposed method is applied to a real case; a corresponding programming code and trick are developed to implement an MCMC simulation in Win BUGS, and a mean time between failures(MTBF) of 1057.9 h is obtained. Given its ability to combine expert judgment, prior information, and data, the proposed reliability modeling and assessment method under the zero failure of NCMTs is validated.

Carbon Emission Modeling and Analysis in Manufacturing Process for Numerical Control Machine Tools

Reducing carbon emissions( CEs) is the urgent demand all over the world. In order to realize the low-carbon numerical control( NC) machining, the evaluation model of a part's manufacturing carbon emission with NC machine tools was built by considering the influences of the cutting tool geometrical parameters.The manufacturing CEs were produced by electric power,cutting tools,and cutting fluid consumed in manufacturing process. The parameters of cutting tools affected not only the CEs,but also the machining quality. Then the actual constraint models of the machine performance,machining quality were given in order to optimize the cutting parameters and achieve the low-CEs. Finally,a case was given to analyze the influences of the cutting tool angles on the manufacturing CEs. The results show that the CEs decrease as the rake angle and edge angle increase under the constraints of the machine specifications and machining quality.

Specialized Numerical Control Plasma Cutting Machine

The large thermal cutting equipment——The DHG. CNC numerical control plasma cutting machine is produced by The Ha’erbin Welding & Cutting Equipment Co. It specializes in the precise formation and baiting of nonferrous boards and thin carbon steel plates at a high speed. It avoids the disadvantage of flame cutting, which cannot cut nonferrous and thin steel plates.

Importance Analysis on Subsystem of CNC Lathe Based on TOPSIS

An importance analysis model for computer numerical control(CNC)lathe subsystems was proposed.The model was based on technique for order preference by similarity to an ideal solution(TOPSIS)and considered the structure correlation between subsystems and the complete machine,the fault correlation of each subsystem and so on.The model can obtain a comprehensive sequencing of subsystems based on their importance to the complete machine.It lays a theoretical foundation for reliability allocation.

Reliability Analysis of Electrical System of Computer Numerical Control Machine Tool Based on Bayesian Networks

The core of computer numerical control(CNC) machine tool is the electrical system which controls and coordinates every part of CNC machine tool to complete processing tasks, so it is of great significance to strengthen the reliability of the electrical system. However, the electrical system is very complex due to many uncertain factors and dynamic stochastic characteristics when failure occurs. Therefore, the traditional fault tree analysis(FTA) method is not applicable. Bayesian network(BN) not only has a unique advantage to analyze nodes with multiply states in reliability analysis for complex systems, but also can solve the state explosion problem properly caused by Markov model when dealing with dynamic fault tree(DFT). In addition, the forward causal reasoning of BN can get the conditional probability distribution of the system under considering the uncertainty;the backward diagnosis reasoning of BN can recognize the weak links in system, so it is valuable for improving the system reliability.

大型CNC机床柔性随行夹具的开发与实现

为了解决大型结构件数控加工时,传统加工固持技术工装数量多、工艺准备时间长、加工连续性差等问题,设计了一种柔性随行夹具。该夹具采用旋摆气缸代替传统压板,根据机床刀具运行轨迹自动控制夹具避让主轴刀头,同时可通过调节压板长度以适应不同形状的工件,具备一定的柔性扩展能力,可应用在三坐标双主轴数控龙门铣床——V22500B或性能参数类似的数控机床上。

Optimization of Numerical Control Program and Machining Simulation Based on VERICUT

In the machining process of large-scale complex curved surface,workers will encounter problems such as empty stroke of tool,collision interference,and overcut or undercut of the workpieces.This paper presents a method for generating the optimized tool path,compiling and checking the numerical control(NC)program.Taking the bogie frame as an example,the tool paths of all machining surface are optimized by the dynamic programming algorithm,Creo software is utilized to compile the optimized computerized numerical control(CNC)machining program,and VERICUT software is employed to simulate the machining process,optimize the amount of cutting and inspect the machining quality.The method saves the machining time,guarantees the correctness of NC program,and the overall machining efficiency is improved.The method lays a good theoretical and practical foundation for integration of the similar platform.

Toolpath Interpolation and Smoothing for Computer Numerical Control Machining of Freeform Surfaces: A Review

Driven by the ever increasing demand in function integration,more and more next generation high value-added products,such as head-up displays,solar concentrators and intra-ocular-lens,etc.,are designed to possess freeform(i.e.,non-rotational symmetric)surfaces.The toolpath,composed of high density of short linear and circular segments,is generally used in computer numerical control(CNC)systems to machine those products.However,the discontinuity between toolpath segments leads to high-frequency fluctuation of feedrate and acceleration,which will decrease the machining efficiency and product surface finish.Driven by the ever-increasing need for high-speed high-precision machining of those products,many novel toolpath interpolation and smoothing approaches have been proposed in both academia and industry,aiming to alleviate the issues caused by the conventional toolpath representation and interpolation methods.This paper provides a comprehensive review of the state-of-the-art toolpath interpolation and smoothing approaches with systematic classifications.The advantages and disadvantages of these approaches are discussed.Possible future research directions are also offered.

Radial Basis Function Interpolation and Galerkin Projection for Direct Trajectory Optimization and Costate Estimation

This work presents a novel approach combining radial basis function(RBF)interpolation with Galerkin projection to efficiently solve general optimal control problems.The goal is to develop a highly flexible solution to optimal control problems,especially nonsmooth problems involving discontinuities,while accounting for trajectory accuracy and computational efficiency simultaneously.The proposed solution,called the RBF-Galerkin method,offers a highly flexible framework for direct transcription by using any interpolant functions from the broad class of global RBFs and any arbitrary discretization points that do not necessarily need to be on a mesh of points.The RBF-Galerkin costate mapping theorem is developed that describes an exact equivalency between the Karush-Kuhn-Tucker(KKT)conditions of the nonlinear programming problem resulted from the RBF-Galerkin method and the discretized form of the first-order necessary conditions of the optimal control problem,if a set of discrete conditions holds.The efficacy of the proposed method along with the accuracy of the RBF-Galerkin costate mapping theorem is confirmed against an analytical solution for a bang-bang optimal control problem.In addition,the proposed approach is compared against both local and global polynomial methods for a robot motion planning problem to verify its accuracy and computational efficiency.

数控机床加工精度的主要影响因素及优化路径探析

数控机床是工业发展的重要基础,拥有优良的使用性能,可以有效提升零部件的加工精度。但是,应用过程中,许多客观因素会影响数控机床的加工精度。笔者结合多年的数控机床检测经验,分析和探究影响数控机床加工精度的相关因素,并提出相应的解决策略,能够为数控机床的加工和使用提供借鉴。

A framework from point clouds to workpieces

Combining computer-aided design and computer numerical control(CNC)with global technical connections have become interesting topics in the manufacturing industry.A framework was implemented that includes point clouds to workpieces and consists of a mesh generation from geometric data,optimal surface segmentation for CNC,and tool path planning with a certified scallop height.The latest methods were introduced into the mesh generation with implicit geometric regularization and total generalized variation.Once the mesh model was obtained,a fast and robust optimal surface segmentation method is provided by establishing a weighted graph and searching for the minimum spanning tree of the graph for extraordinary points.This method is easy to implement,and the number of segmented patches can be controlled while preserving the sharp features of the workpiece.Finally,a contour parallel tool-path with a confined scallop height is generated on each patch based on B-spline fitting.Experimental results show that the proposed framework is effective and robust.

Numerical Diffusion Control of a Space-Time Discontinuous Galerkin Method

Variations on space-time Discontinuous Galerkin(STDG)discretization associated to Runge-Kutta schemes are developed.These new schemes while keeping the original scheme order can improve accuracy and stability.Numerical analysis is made on academic test cases and efficiency of these schemes are shown on propagating pressure waves.

The Mechanical Strength Property of Brick Material and its Impact on the Processing Quality

A large number of experiments have been done for analyzing the two important indicators -compressive strength and flexural strength,which affect computer numerical control (CNC) engraving material physical properties.Using Matlab for simulation experiment,the processing quality of different intensity brick materials is analyzed by the theory of fracture toughness.The result show that porosity is an important factor for engraving,and the research also provide a reference for further study which can improve the quality of brick carving.

Fuzzy Tuned PID Controller for Envisioned Agricultural Manipulator

The implementation of image-based phenotyping systems has become an important aspect of crop and plant science research which has shown tremendous growth over the years. Accurate determination of features using images requires stable imaging and very precise processing. By installing a camera on a mechanical arm driven by motor, the maintenance of accuracy and stability becomes non-trivial. As per the state-of-the-art, the issue of external camera shake incurred due to vibration is a great concern in capturing accurate images, which may be induced by the driving motor of the manipulator. So, there is a requirement for a stable active controller for sufficient vibration attenuation of the manipulator. However, there are very few reports in agricultural practices which use control algorithms. Although, many control strategies have been utilized to control the vibration in manipulators associated to various applications, no control strategy with validated stability has been provided to control the vibration in such envisioned agricultural manipulator with simple low-cost hardware devices with the compensation of non-linearities. So, in this work, the combination of proportional-integral-differential(PID) control with type-2 fuzzy logic(T2-F-PID) is implemented for vibration control. The validation of the controller stability using Lyapunov analysis is established. A torsional actuator(TA) is applied for mitigating torsional vibration, which is a new contribution in the area of agricultural manipulators. Also, to prove the effectiveness of the controller, the vibration attenuation results with T2-F-PID is compared with conventional PD/PID controllers, and a type-1 fuzzy PID(T1-F-PID) controller.

Improved time-optimal B-spline feedrate scheduling for NURBS tool paths in CNC machining

Feedrate scheduling in computer numerical control(CNC)machining is of great importance to fully develop the capabilities of machine tools while maintaining the motion stability of each actuator.Smooth and time-optimal feedrate scheduling plays a critical role in improving the machining efficiency and precision of complex surfaces considering the irregular curvature characteristics of tool paths and the limited drive capacities of machine tools.This study develops a general feedrate scheduling method for non-uniform rational B-splines(NURBS)tool paths in CNC machining aiming at minimizing the total machining time without sacrificing the smoothness of feed motion.The feedrate profile is represented by a B-spline curve to flexibly adapt to the frequent acceleration and deceleration requirements of machining along complex tool paths.The time-optimal B-spline feedrate is produced by continuously increasing the control points sequentially from zero positions in the bidirectional scanning and sampling processes.The required number of knots for the time-optimal B-spline feedrate can be determined using a progressive knot insertion method.To improve the computational efficiency,the B-spline feedrate profile is divided into a series of independent segments and the computation in each segment can be performed concurrently.The proposed feedrate scheduling method is capable of dealing with not only the geometry constraints but also high-order drive constraints for any complex tool path with little computational overhead.Simulations and machining experiments are conducted to verify the effectiveness and superiorities of the proposed method.

一种专用数控机床微机控制系统的设计与实现

本文论述了一种基于８０８８ＳＴＤ总线的工业控制计算机应用系统的设计与实现，该系统用于一种专用的数控机床。

A new principle and device for large aircraft components gaining accurate support by ball joint

How to obtain an accurate support for large components by ball joint is a key process in aircraft digital assembly. A novel principle and device is developed to solve the problem. Firstly, the working principle of the device is introduced. When three or four displacement sensors installed in the localizer are touched by the ball-head, the spatial relation is calculated between the large aircraft component's ball-head and the localizer's ball-socket. The localizer is driven to achieve a new position by compensation. Relatively, a support revising algorithm is proposed. The localizer's ball-socket approaches the ball-head based on the displacement sensors. According to the points selected from its spherical surface, the coordinates of ball-head spherical center are computed by geometry. Finally, as a typical application, the device is used to conduct a test-fuselage's ball-head into a localizer's ball-socket. Positional deviations of the spherical centers between the ball-head and the ball-socket in the x, y, and z directions are all controlled within ±0.05 mm under various working conditions. The results of the experiments show that the device has the characteristics of high precision, excellent stability, strong operability, and great potential to be applied widely in the modern aircraft industry.

Thermal error modeling based on BiLSTM deep learning for CNC machine tool

The machining accuracy of computer numerical control machine tools has always been a focus of the manufacturing industry.Among all errors,thermal error affects the machining accuracy considerably.Because of the significant impact of Industry 4.0 on machine tools,existing thermal error modeling methods have encountered unprecedented challenges in terms of model complexity and capability of dealing with a large number of time series data.A thermal error modeling method is proposed based on bidirectional long short-term memory(BiLSTM)deep learning,which has good learning ability and a strong capability to handle a large group of dynamic data.A four-layer model framework that includes BiLSTM,a feedforward neural network,and the max pooling is constructed.An elaborately designed algorithm is proposed for better and faster model training.The window length of the input sequence is selected based on the phase space reconstruction of the time series.The model prediction accuracy and model robustness were verified experimentally by three validation tests in which thermal errors predicted by the proposed model were compensated for real workpiece cutting.The average depth variation of the workpiece was reduced from approximately 50μm to less than 2μm after compensation.The reduction in maximum depth variation was more than 85%.The proposed model was proved to be feasible and effective for improving machining accuracy significantly.