Unigraphics NX/CAM CNC milling programming
I. Introduction
Unigraphics supports General Motors in the world's largest VPD implementation project. Unigraphics became the standard for Denso, Japan's leading auto parts manufacturer. More than 10,000 sets of UGs have been installed in the US aerospace industry. Unigraphics occupies 90% of the Russian aviation market and 80% of the North American gasoline reel engine market, with customers such as Pratt & Whitney GE jet engines, and other aerospace customers including: BEAerospace, Boeing, Israel Aircraft Industries (IAI) and British Aerospace Airlines, etc., in the fields of machinery, medical equipment, electronics, high technology and consumer goods industries, customers include 3M, DEC, Philips and other companies.
UnigraphicsNX is a parametric and characterization CAD/CAM/CAE system that integrates wireframe model, surface modeling and solid modeling. The system is built on a unified and relational database, providing complete correlation in engineering, so that CAD/CAM/CAE data can be switched freely. With the basic features as the basic unit of interaction, using the feature technology, users can carry out product design, mold design, CNC machining programming and engineering analysis at a higher level, and realize the integration and linkage of parallel engineering CAD/CAPP/CAM. This not only facilitates the exchange of information between CAD/CAM systems, but also facilitates the sharing of information. Applying the powerful CNC machining programming functions provided by Unigrahpics NX, including CNC turning, milling, wire cutting and other programming modules, is an important way to improve the application level of CNC machining technology.
Second, Unigraphics NX / CAM CNC milling programming
Unigrahics NX/CAM has the following important components: 3D modeling, tool path design, tool path editing and modification, machining simulation, post processing, CNC programming template, cutting parameter library design and secondary development function interface.
CNC programming template
The use of CNC programming templates facilitates the use of existing experience and expert knowledge to achieve the purpose of sharing resources within the enterprise. The system provides the machining program template, tool template, machining object template and tool path template. In the template, the knowledge, experience and habits of CNC programmers, processing technicians and skilled workers are continuously injected to establish a standardized CNC machining process, which lays a good process technology for strengthening production management and improving product processing efficiency and quality. basis. The CAM system creates the user's own template to set the pre-processing sequence, process parameters and cutting parameters. For similar parts processing objects, the application template can greatly improve the efficiency and quality of numerical control programming, especially in the mold industry for the processing of similar groups of parts. For example, when manufacturing a mold, the best process for machining the punch and the die is defined as a machining template. When processing a new product object, simply call the template file, select the desired geometry, and start the process. . The expert-level manufacturing process guidance is easily obtained from the template by the user through the machining wizard. Through the wizard, pre-defined templates can be activated and quickly generate CNC machining tool tracks with simple interaction.
The Unigraphics NX system provides a basic CNC programming template. Take the Shops_diemould template set as an example. The configuration file Shops_diemold.dat is located in the mach esourceconfiguration, and the template set file Shops_diemold.opt is located in the mach esource emplate directory. Users can create their own programming templates for rough programming, tools, products, etc. based on the experience of the company. Before using the template, it is necessary to organize and collect templates for different processing methods of parts of different product categories. When creating a template, it can be classified according to the processing method. For serialized or similar processing techniques, such as the processing of convex and concave mold parts, it can include complete machining process templates such as rough finishing scheme, tool and process parameter selection. The definition of the template can be divided according to the processing requirements and geometric features of the product, or according to the processing requirements and materials of the product.
2. Tool path generation
The system provides point programming modules for drilling cycle, tapping and boring, with a variety of contouring, contour cutting, row cutting and island machining plane milling. It provides fixed axis and variable axis machining programming functions for 3 to 5 coordinate complex surfaces. It can control the vector direction of the tool axis arbitrarily. It has surface contour, contour stratification, parameter line machining, curved streamline, steep bevel and surface clearing. Various tool path control methods such as root.
(1) UG/Planar Milling (UG plane milling)
UG plane milling module function, including multiple pass contour milling, contouring inner cavity milling, zigzag milling milling, specifying the safety margin to avoid the fixture and internal movement, providing cavity layered cutting function, cavity bottom surface The island processing function, which defines the boundaries and the geometry of the wool, shows the boundaries of the uncut areas, and provides some instructions for operating the machine's auxiliary motion, such as cooling, tool compensation, and clamping.
(2) UG/Core & CavityMilling (UG core, cavity milling)
UG core and cavity milling can be used to rough out single or multiple cavities. It can remove large amount of roughing along the shape of any similar core, and generate tool movement trajectory for very complicated shapes. . Through tolerance cavity milling, the design accuracy is low, and there are gaps and overlapping shapes between the curved surfaces, and the surface of the cavity can be up to hundreds. When the profile is abnormal, it can be corrected by itself or specified by the user. The cavity is machined within the tolerance range.
(3) UG/Fixed AxisMilling (UG fixed axis milling)
UG fixed axis milling module function, including 3 axis linkage machining tool path function, machining area selection function, a variety of driving methods and pass mode are available, such as cutting along the boundary, radial cutting, spiral cutting and user-defined cutting Wait. In the boundary drive mode, a variety of cutters such as concentric circles and radial cutters can be selected to provide up-cut, down-milling control and spiral feed mode, which automatically identify unprocessed areas and steep sections that cannot be removed in the previous process. Zones so users can further clean up these places.
(4) UG/Flow Cut (UG automatic clearing)
Automatically find the area on the part to be machined that satisfies the “double tangency conditionâ€. In general, these areas are just the root zone and corner in the cavity. The user can directly select the machining tool, and the UG/Flow Cut module will automatically calculate the “Double Tangent Condition†area corresponding to this tool and use it as the drive geometry to automatically generate one or more passes. This module reduces the amount of finishing or semi-finishing work when complex core or cavity machining occurs.
(5) UG/Variable Axis Milling (UG Variable Axis Milling)
The variable-axis milling module supports both fixed-axis and multi-axis milling functions, which can process any geometry generated in the UG modeling module and maintain the correlation of the main model. This module provides 3 to 5 axis milling functions that have been validated for many years, providing tool axis control, pass mode selection and tool path generation.
(6) UG/Sequential Milling
The UG sequential milling module can realize the following functions: control each step of the tool path generation process, support 2 to 5 axis milling programming, and is completely related to the UG main model, and can obtain absolute control similar to APT direct programming in an automated manner. Allows the user to interactively generate tool paths over a period of time and maintain control of each step in the process. It provides a looping function that allows the user to define only the innermost and outermost toolpaths on a surface, and the module automatically generates intermediate steps. This module is a unique module such as automatic clearing root in UG CNC machining module, which is suitable for difficult NC programming.
(7) Support for high speed milling
The contoured processing provided by the system is applied to high-speed milling occasions, and the corners are transferred in the form of rounded corners to avoid the 90° sharp turn (the rails and the motor are easily damaged in high-speed occasions), and the spiral advance and retreat cutters are used, and the system also provides surrounds and the like. A variety of ways to support the generation strategy of high-speed machining tool path.
3. Tool shaft guiding method
Space surface axis machining involves more content, especially when five-axis machining is more obvious. When performing five-axis machining, it involves key technologies such as machining of guide surfaces, interference surfaces, trajectory limitation areas, advance and retract knives, and tool axis vector control. One of the key techniques for four-axis five-axis machining is to understand the spatial variation of the tool axis vector (axis vector of the tool axis). The vector change of the tool axis is achieved by swinging the table or spindle. For fixed-axis milling where the vector does not change, the product is usually machined by three-axis milling. The key to the five-axis machining is to control the tool axis vector in the spatial position or to make the tool axis vector and the machine's original coordinate system form a certain angle in the space, using the side or bottom edge cutting of the milling cutter. The vector change control of the tool axis generally has several ways as shown in FIG.
4. Editing and editing of tool path
The module can observe the movement of the tool along the trajectory in graphical mode and make graphical changes. It has the functions of copying, editing and modifying the tool position file, defining the tool, machine tool and cutting parameter database (such as extending or shortening the tool path). Modifications, etc., can be flexibly customized and tailored according to user requirements.
5. Machining simulation
The cutting simulation module UG/Vericut is a third-party module integrated in UG software. It uses human-computer interaction to simulate, verify and display NC machining programs. It is a convenient way to verify NC programs. By eliminating the steps of testing the sample, the machine debugging time can be saved, and tool wear and machine cleaning can be reduced. By defining the blank shape of the cut part and calling the NC location file data, the correctness of the tool path generated by the NC can be verified. UG/Vericut can display post-processed and colored part models, allowing users to easily check for incorrect machining conditions. As another part of the test, the module can also calculate the volume of the machined part and the amount of blank removed, so it is easy to determine the loss of raw materials. Vericut offers a number of features, including a full graphical display of blank size, position and orientation, for 2- to 5-axis simultaneous milling and drilling.
6. Post processing
The most important thing in post processing is to convert the tool path generated by CAM software into an NC program suitable for CNC system machining. By reading the tool position file, coordinate motion transformation and command format conversion are performed according to the machine motion structure and control command format. The general post-processing program is based on the standard tool path and the motion configuration and control commands of the general CNC system. It includes machine coordinate motion transformation, nonlinear motion error check, feed speed check, NC program format conversion and NC program output. Only by using the correct post-processing system can the tool path trajectory be output as a numerical control program for the machine tool of the corresponding CNC system to be correctly processed. Therefore, the preparation of the correct post-processing system template is one of the prerequisites for NC programming and machining. The main content of post-processing includes three aspects.
(1) The output of the CNC system control command mainly includes the machine type and machine tool configuration, machine tool positioning, interpolation, spindle, feed, pause, cooling, tool compensation, fixed cycle and program head and tail output.
(2) Format conversion Including data type conversion and rounding, string processing, etc., mainly for the output format of the CNC system, such as unit, output address characters and other aspects of control.
(3) Algorithm processing Mainly for coordinate transformation, cross-quadrant processing and feed rate control in multi-coordinate machining.
UG/Post Execute and UG/Post Builder form the post processing of the UG processing module. UG's post processing module allows users to easily create their own post processing routines. This module is suitable for almost all mainstream NC machine tools and machining centers in the world. It has been proven to be suitable for milling of 2 to 5 axes or more in many years of application practice, 2 to 4 axes of turning and wire EDM. . The UG/Nurbs Path Generator spline trajectory generator module allows toolpath data based on Nurbs splines to be generated directly in the UG software, resulting in a higher accuracy and smoothness of the generated trajectory, while the processing program is 30% less than the standard format. 50%, the actual machining time is greatly shortened because it avoids the waiting time of the machine controller. This module is a must-have tool for users who want to use a high-speed milling machine (FANUC or SIEMENS) with spline interpolation. When using UG/Post Builder for post-processing new creation, editing and modification, three files are generated: the function and format definition file of the machine control system *.def, and the machine tool motion event processing file *.tcl and utilization are written in Tcl language. The PostBuilder editor sets the parameter file *.pui for all data information. The post-processing program closely integrates the CAM system with the CNC machining of the machine tool through the machine's CNC system.
7. Cutting parameter library design
Using the system library, you can get data on machine tools, tools and materials, part materials, cutting process methods, spindle speed and feed rate, define standardized tool magazines, and process parameter library for machining, roughing, semi-finishing, finishing, etc. Standardize common operating parameters to reduce training time and optimize machining processes, providing a database of stored tools and cutting parameters and standard tool commands. Users modify the data in the library to meet the needs of the enterprise.
8. CAM secondary development function interface
The system provides a secondary development interface. The user can use C language, use Visual C++ as the integrated development environment, and develop professional numerical control programming functions to further improve programming efficiency and simplify operation. The C language header function provided is located in the UG OPEN directory, including Uf_cam.h, Uf_camgeom.h, Uf_cam_planes.h and other header files. The main contents of several important header files are as follows.
(1) Uf_cam.h
It mainly defines some information about system processing, such as enumeration, structure and system startup entry settings, initialization of the application application to load the application, access to the system function of the system machine tool, tool, processing object and so on.
(2) Uf_cam_planes.h
Defines the planar data information involved in system programming, such as defining, editing, accessing the origin and normal of the plane, setting and accessing the state information of the plane, etc.
(3) Uf_cambnd.h
Used to define settings and get boundary information.
(4) Uf_camgeom.h
Contains properties and methods for defining settings and getting geometry objects for NC machining.
Third, UnigrahpicsNX / CAM CNC programming process
Unigraphics NX/CAM is used for CNC machining of product parts. The flow is generally as follows.
The first is to call the product part to load the blank, call the system template or the user-defined template; then create the machining program, define the machining object, design the tool, define the machining method and generate the corresponding machining program; The contents of the program, such as the specific content of the machining object, the guiding method of the tool, the cutting step, the spindle speed, the feed amount, the cutting angle, the advance and retraction point, the interference surface and the safety plane, etc. After the simulation processing, the tool path is edited, modified, copied, etc.; after all the tool path design is qualified, post-processing is performed to generate the processing code of the corresponding CNC system for DNC transmission and NC machining. The Unigraphics NX/CAM system offers a wide range of machining object definitions, tool axis guidance and tool path versatility.
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