Virtual NC Research Articles

A motion control method for face hobbing on CNC hypoid generator

In this paper, the relative motion relation was derivated among the virtual cradle, generating gear, cutter and workpiece on the CNC hypoid generator. A directly axis coordinate solving method of CNC hypoid generator was proposed by taking cutter axis vector as control objectives to transform the attitude of whole cradle-type generator. The method didn't solve complex nonlinear equations. We also provide a motion control solution for face-hobbing on the CNC hypoid generator using Siemens 840Dsl NC system.In this method, the online real-time programming is achieved, because of the index motion and generating motion of machining process are separated, and spline interpolation and electronic gearbox function are adopted. The tooth form equation which is determined by the motion control model of CNC hypoid generator is derived. The calculation example of a gear sets shows that the theoretical tooth form of the epicycloid hypoid gear machined by such motion control method is consistent with the standard tooth form computed by Gleason CAGE Software. With NC machining simulation software VERICUT, virtual NC hypoid gear cutting machine is established, which realizes face hobbing simulation of such gear sets. At last, a face hobbing experiment is conducted on YK2235 CNC hypoid generator manufactured by Tianjin No. 1 Machine Tool Works, and such face hobbing motion control model is verified as correct through tooth form measurement and rolling test.

Researched on the Technology of Machining Simulation

The machine tool machining is a major processing method in manufacturing industry. Achieved the simulation for the machining process will greatly improved the processing efficiency, perfected the processing quality and reduced the production costs. It has important significance for the development of modern manufacturing industry. This paper studied the constitute of the processing verification and simulation systems. And focuses on the principle of the machine tool system driven by the common simulation engine and driven by the virtual NC controller. Finally, the simulation system was built and use the blade machining as an example to the simulation test and verify.

Research on Simulation of Virtual NC Lathe Machining Process

Virtual NC lathe machining simulation system is carried out with Visual C++ and Open Inventor software. The system possesses visible UI, interactive inputting workpiece and machining parameters, the integration of geometric simulation and physical simulation, all the simulation functions including real-time display machining process, tool moving, workpiece geometry shape change, the generation and movement of iron simulation, workpiece pressure shape change could be realized. Tool temperature analysis and stress & strain analysis are simulated in the cutting process by FEM. The simulation results show the high efficiency of the simulation algorithm, reasonable simulation results, lifelike. The practice and training could be replaced by the virtual one. The system is applied to verification of NC code, quality evaluation of machine operators, operators, CNC programming staff training and other functions.

Research on Finite Element Simulation Processing Method for Flatness Prediction

The prediction of flatness is researched based on the simulation of virtual NC manufacture process. In this paper, a new interpolation-regression model is proposed, which is based on the simulation method of the finite element analysis and depends on MATLAB to realize the calculated algorithm of flatness error. In the model, on the premise of that the workpiece is completed the simulation, the information of numerous discrete points is acquired from the virtual workpiece. A new surface which is much closer to the workpiece morphology is generated by interpolation theory with statistics toolbox of MATLAB. The assessed datum of flatness is concluded by the theory of the multivariate linear regression. Synthesizing the original points and the created datum, the work calculates the flatness error and develops the flatness predicted system of virtual workpiece. The system can realize the vivid man-computer interaction in MATLAB.

Design and Implementation of Virtual NC Real-Time Machining Process Control System

After the virtual NC real-time machining process control technology is studied, we design the NC code interpreter using the pipeline control method of overlapped resources in this paper. In order to improve the availability of interpreter, the design adopts the function pointer array and expression evaluation algorithm. By using two methods, the scalability is enhanced. Also the versatility is improved by using keywords information table to some extent. The system achieves a straight line and arc of the trajectory interpolation by the digital sampling algorithm and makes the efficiency improved by using RCS communication mechanism, windows thread and timing mechanism.

Virtual Machining of Spiral Bevel Gear Based on VERICUT

Spiral bevel gear milling machine is one typical representative of complex manufacturing equipments. In order to simulate spiral bevel gear cutting, a five-axis virtual CNC gear cutting machine under VERICUT software is established in this paper. Based on a spiral bevel gear generating theory, the surface forming of the spiral bevel gear is studied by using coordinate transformation method in spatial kinematics, and the G-code required by actual gear cutting is generated. Then, according to the properties of the general five-axis CNC system, the machine model and the relevant configuration parameters under VERICUT is created, so the spiral bevel gear virtual NC machining system is set up. Finally, the cutting simulation and crash examination are accomplished under VERICUT. By using this method, the accuracy of the bevel gear cutting system based on a general five-axis CNC can be well verified.

Virtual System of NC Milling Based on 3ds Max and Open GL Modeling

This virtual system, which is based on virtual manufacturing and NC processing technique for NC milling, is developed by Visual C++6.0. The system can edit, check and debug the NC programs to realize the 3D dynamic simulation of machining processes and collision-checking during cutting processes.

Research on Modeling of Ball-End Cutter for Virtual NC Machining

In this paper, a new mathematical model and modeling method of ball-end milling cutter which satisfies the request of physical simulation in virtual NC machining system are proposed. The accurate expressions of the cutting edge are presented. The precise functional surface model of ball-end cutter is developed. And the 3-D visualization for ball-end milling cutter in virtual NC machining is implemented. The model can provide necessary and accurate geometric information for physical simulation and has been applied in milling force simulation. It laid the foundation for integration of geometric simulation and physical simulation.

Research on Parameters Optimization of Virtual NC Milling Based on Parallelism Selection Genetic Algorithm

To resolve key technology of parameter optimization of virtual NC milling physical simulation system, a multi-objectives optimized model was set up by non-linear programming theory and resolved by improved parallelism selection genetic algorithm. It was optimized when milling characters are sufficiently considered and machine quality was guaranteed. Sub-population size is decided by weighting each optimized object and calculating adaptation to assure importance of optimized objects and fasten convergence velocity. A kind of software that can optimize milling parameters of virtual NC was developed, and optimized strategy and validity of algorithm are verified which provides technology support for realizing virtual NC milling physical system.

Digital manufacture of large-grade hydro turbine's blades

The blade is one of the vital components and the most difficulty in manufacturing of large hydro turbines. In order to cost-effectively and productively manufacture these kinds of blades, a series of innovative digital techniques have been developed. It includes the digital design of hydro turbine blades based on manufacturers’ requirements, computer-aided location and the machined error evaluation with three-dimensional digitized measure, tool path generation strategy for enhancing machining efficiency and controlling deviation in NC machining, tool path generation and NC machining simulation by means of a virtual NC machining environment for blades, and feasible strategy and the systematic scheme for manufacturing of large blades with 5-axis simultaneous CNC machining technology. The developed innovative digital manufacture techniques have been successfully applied in the manufacturing of both the large grade Kaplan and Francis hydraulic turbine blades. It has been shown that the higher efficiency and the better surfaces finish accuracy can be achieved in practical engineering.

Modeling and Simulation of Milling Force in Virtual Numerical Control Milling Process

A parameter equation based on cutting edge of ball-end mill is set up by analyzing the parameters of ball-end mill influence the milling force in virtual NC milling process. The relationship among elemental cutting force, instantaneous radial chip thickness and cutting edge length is analyzed, and the dynamic milling force of ball-end mill at arbitrary feed direction is established. The milling force parameter model by quadratic regression equation in different cutting conditions is built. Through experiments in NC machining center and using orthogonal combination and principal components analysis, the regression coefficients are calculated. The correctness of milling force model is testified by experiments. All these can provide theoretical basis for physics modeling and simulation of virtual numerical control milling.

Virtual Optimization of Machine Tools and Production Processes

Faster development of innovative machine tools, shorter processing times, improved surface quality of workpieces, higher machine productivity – these are just a few of the wishes and demands of machine manufacturers and end-users. Time-to-market is decisive; in some industries, six months too late on the market can already be decisive in losing the race for market leadership. The key to success lies in virtual techniques. These are an extremely cost-effective way to increase productivity in all phases of the machine tools life cycle. Siemens AG, the leading provider for control and drive technology, sees itself as a partner for the whole machine tool industry and offers four phases of simulation support which cover the entire life cycle of a machine: Mechatronic Support for simulation for machine development, Machine Simulator for supporting commissioning, Virtual Production for the optimization of production and, finally, Virtual NC Kernel (VNCK) for the testing of NC part programs at the end-user.

디지털 매뉴팩쳐링 기법을 이용한 절단기기의 검증된 가상 NC 시뮬레이터 구축

Digital manufacturing is a technology to simulate the real manufacturing process using the virtual model representing the physical schema and the behavior of the real manufacturing system including resources, processes and product information. Therefore, it can optimize the manufacturing system or prevent the bottleneck processes through the simulation before the manufacturing plan is executed. This study presents a method to apply the digital manufacturing technology for the steel cutting process in shipyard. The system modeling of cutting shop is carried out using the IDEF and UML which is a visual modeling language to document the artifacts of a complex system. Also, virtual NC simulators of the cutting machines are constructed to emulate the real operation of cutting machines and NC codes. The simulators are able to verify the cutting shape and estimate the precise cycle time of the planned NC codes. The validity of the virtual model is checked by comparing the real cutting time and shape with the simulated results. It is expected that the virtual NC simulators can be used for accurate estimation of the cutting time and shape in advance of real cutting work.

A virtual non contact-atomic force microscope (NC-AFM): Simulation and comparison with analytical models

A virtual NC − AFM machine has been built using the Matlab language. The virtual NC − AFM is identical to a real hybrid machine built with Digital Instruments and Omicron blocks. The role of every subset is described in detail, and special attention is paid to the parameters of the Automatic Gain Control (AGC) which controls the amplitude of the oscillations. The virtual machine is a powerful tool, that allows to solve, without any approximation, non linear coupled differential equations describing the physics of the tip-surface interaction. The machine is then used to study the frequency shift and damping signal in the approach-retract mode. Two types of situations are analyzed: the first one corresponds to the case where no dissipative force is introduced in the tip-surface interaction, the second one deals with dissipative forces. These last ones are here introduced by assuming a mechanical deformation of the surface under the tip. Interesting results are then obtained, in particular the fact that unstability may occur under some particular conditions. Most of the results obtained by simulation are then compared with those of analytical models already published in the literature.