NC Machining Process Research Articles

Study on Numerical Control Machining Technology of Full-Surface Part

A complex part, which has curved surface overall, is trial-manufactured with CNC machine. The NC machining process and technology of this full-surface part are studied in this paper. First, the 3D model of the part is created in the modeling module of UG system. Then, process analysis and scheme are developed. As the part has an irregular shape and the entire surface is to be NC machined, there are many difficulties during processing. The optimized process plan is determined. In the manufacturing module of UG system, the NC machining parameters are set according to the processing requirements, the tool paths are generated, edited and checked, and the NC code is generated by post processing. Finally, the part is manufactured using a 3-axis CNC milling machine with the NC programs. It has desirable shape and high accuracy. The result shows that the NC process is reasonable and efficient. CAD/CAM integration technology is applied successfully in this example. The methodology and technology introduced in this paper can provide valuable reference for processing similar parts, and it is also useful for correlational study.

Study on CNC Machining Method of EDM Copper Electrode

The structural feature of EDM copper electrode is analyzed in this paper from the aspect of machining process, and the NC machining process is studied. The CNC machining method of EDM copper electrode is described briefly; the problem that frequently occurs in the machining that the copper electrode is deformed is solved, and the machining criterion of EDM copper electrode is discussed as well.

CNC Lathe Circular Interpolation Principle and Technological Parameters Research and Positive and Negative Arc Running Direction Analysis

Compiled nc programs, perfect quality parts processing of nc machining process, is compiling personnel, nc machining operation personnel most concern. This paper discusses correct understanding circular interpolation principle and processing technology analysis[1]; When the manual programming how correct establishment self-positioning presended car parts, accurate discriminant number of circular interpolation instructions as an example, this paper expounds the direction of running direction accurately arc discriminant method, remove programming staff for professional too strong and difficult to understand the confusion generated.

The Analysis of Effects of Curvature Attribute on Interference in Freeform Surface Blade NC Machining

This paper proposes the Gaussian Curvature by analyzing the free surface of the blade surface curvature, which is based on the Gaussian Curvature parameter mapping method to study the Gaussian curvature of free surface NC machining process interference. We introduce the conception of curvature to analyze the curvature and optimize the cutting parameter and cutting tool parameter to avoid interference phenomena happening and improve the processing efficiency and precision. Take the ball end cutter for example to process simulation, it shows that through the analysis of the free surface curvature method to avoid the intervention process is feasible, and has been verified by the experiment.

Study on Key Technologies of Practical DNC System

Aim at the communication problems of computer and NC machine tool, a practical DNC system is developed in this paper. A three-layer control structure mode – which is composed by the unit layer, DNC computer workstation layer and NC system equipment layer – is presented. Based on its good real-time capability and high reliability, CAN field-bus is introduced into the DNC communication system construction, the network topology is constructed and related hardware is chosen properly. Using VC++6.0 as development tool, and assisted with special compiling tools LEX&YACC, 3D standard graphic library OpenGL and database Microsoft Access, and based on the multi-task and multi-thread technologies, the software of the system is developed. The system has the characteristics of reliable operation, simple structure and high real-time capability, can improve the efficiency of NC machining process obviously, and has a certain application prospect in the middle and small scale manufacturing enterprises of our country.

Study on Computer-Aided Optimizing Milling Parameters of Numerical Control Machine

In this paper, the modern theory of milling and the optimization technique are applied to the establishment of the mathematical model of face milling to obtain the optimum face milling parameters, in which the highest productivity is the optimizing objective，and many constraints are taking into consideration．The optimization is programmed based on the complex form method and castigatory function method．And a optimization system is established, the system which is composed of optimizing calculation module, special milling parameters database and man-machine interface．And it is programmed by adopting Visual Basic．The NC milling example is optimized，the validity and practicability of optimizing mathematic model is proved，and the base of the optimization of the NC machining process is established．

Research on the Adaptive Machining Technology of Blisk

Due to different datum position and inevitable distortion from the linear friction welding process, the nominal CAD model from the design stage is no longer suitable for the use of the final NC machining, and that is the main problem for precisely machining complex blisk. In this paper, an adaptive machining approach based on adaptive process model for high precision manufacturing of blisk is proposed and developed. Comparing the nominal model with the inspection result, adaptive process model is reconstructed to describe workpiece localization, allowance distribution and composite error compensation for NC machining of blisk accurately. Firstly, the transformation matrix for allowance optimization is searched fleetly by genetic algorithm with constraint conditions. Secondly, using the cross-section curve blending and deformation compensation method, adaptive model for shape distortion is constructed to solve the part-to-part variation machining problem and to realize precision machining for complex geometry blisk. Finally, based on the adaptive process model, tool paths used for the last NC machining process can then be adaptively generated to implement the different processes work. Example shows that the adaptive machining technology of blisk is feasible and the result is of high precision and efficiency.

Accurate Estimation Method of Intersection Coordinate between View Lines and Curved Surface Using Graphics Hardware

This paper deals with a new calculation algorithm of Z-map representation with graphics hardware to perform geometric simulation of NC machining process. Graphics hardware (GPU) is a device designed to render 3D computer graphics. In previous studies, it is proposed that shape of machined workpiece is estimated by referring depth information on rendered image by GPU. However, such depth information usually contains calculation error that cannot be corrected, because GPU cannot deal with curved surface directly and requires approximation to a polyhedron. In this paper, a new geometric calculation method based on GPU functions is proposed in order to estimate accurate depth information from rendering process. In the proposed method, pixel shader in GPU estimates a distance between the curved surface and the approximated polyhedron in modeling coordinate system and corrects the depth information on frame buffers.

Pocketing toolpath optimization for sharp corners

Abstract In pocket milling, there may be residual material left at sharp corners when stepover is inappropriately large in contour-parallel tool paths. According to this problem, the paper proposes an improved NC toolpath generation strategy in order to optimize NC machining processes for pocket milling. By inserting two types of biarc transition segments in contour-parallel toolpaths, the new method can remove the residual material completely without cutter compensation, produce second order continuous toolpath, and allow the stepover to be as wide as possible to reduce the machining time. A machining experiment has been implemented to validate the efficiency of the method.

Development of simulation system for machining process using enhanced Z map model

To verify NC programs as well as to optimize the cutting conditions, the importance of machining process simulation system is increasing. The paper discusses new approach for milling operation simulation using enhanced Z map algorithm. To extract the required geometric information from NC code, suggested algorithm uses supersampling method to enhance the efficiency of a simulation. By executing redundant Boolean operations in a grid cell and averaging down calculated data, presented algorithm can accurately represent material removal volume though tool swept volume is negligibly small. Supersampling method is the most common form of antialiasing and usually used with polygon mesh rendering in computer graphics. The key advantage of extended Z map is that the data structure is same with conventional Z map, though it can acquire higher accuracy and reliability with same or lower computation time. By simulating machining operation efficiently, this system can be used to improve the reliability and efficiency of NC machining process as well as the quality of the final product.

About the Orthogonal Parameterization of Sculptured Part Surfaces and Initial Tool Surfaces

In the domain of multi-axis NC machining of sculptured surface parts, the use of orthogonal parameterizations of part and tool surfaces is convenient because it simplifies the transformation of coordinate systems. Using the so-called “differential-geometric method of sculptured surface NC machining,” developed by one of the authors, many parameterizations of part and tool surfaces are easily shown not to be orthogonal. To transform nonorthogonal part and tool surface parameterizations into orthogonal ones, the Jacobian of the transformation may be used. In cases when the Jacobian of the transformation is not known, it is possible to use differential equations for isogonal trajectories on the surfaces (choosing an orthogonal case), or a special kinematic method for obtaining sculptured surface equations. Influences of coordinate system transformations (translations and rotations along and about axes through the origin) on example part and tool surface parameterizations for four types of general helicoidal surfaces are described. The results mentioned above simplify the analytical description of the multi-axis NC machining process, and may be useful for writing NC toolpath generation software.