Implementation of NC programming process based on

Realization of NC programming process based on knowledge base

[Abstract]: This paper briefly introduces the secondary development environment using powerfill software, the development method of establishing various common databases based on the actual situation of our company, and the basic process of NC programming using this database

key words: NC programming PowerMILL macro program parameter library machine tool library user menu

I. preface

the application of the company's mold NC processing technology began in the early 1980s, and has accumulated rich experience in NC programming and processing for many years. However, in recent years, with the rapid development of computer technology, programming software technology, high-speed machining technology and other CNC related technologies, as well as more than ten large-scale high-speed CNC machining centers we have invested heavily in, there is an urgent need for a programming method that is not only fast and safe, but also simple, easy to learn and easy to use. PowerMILL software was introduced in 2002 based on this requirement. At the beginning of using the software, many parameters are always input repeatedly, which is easy to make mistakes. The programming quality mainly depends on the programmer's personal software proficiency and programming experience. After a period of exploration, we have used the good openness of the secondary development environment of the software to gradually generate many practical macro program databases of programming methods that integrate the programming software system and the actual processing conditions. These macro programs have been widely used through continuous improvement and change in the past two years. The following is a brief introduction to the development mode of macro program database and the basic process of NC programming using this database

II. Construction methods of various macro program parameter libraries

1 Generation of macro program. The so-called macro programming is to convert a large number of parameters or commands that need to be input frequently into a simple single command through the macro command recording tool provided by the software. After the macro program is generated, the corresponding is a text file, which can be modified with a texter. Using macro program can quickly integrate the programming and processing specifications and personal programming and processing experience into a standard file and promote its application. The recording of macro program is relatively flexible. Anyone can record and use it at any time, and can also use it for combination. During the recording process, we must pay attention to the logic of the program sequence. The processing parameters between different processing strategies cannot affect each other. If necessary, we should use the reset command to restore the software parameters to the startup state

2. Construction of processing template library. The concept of machining template is provided after powermillv4.5. The tool path template is a template file that fills in the relevant values in the tool path strategy table, which is related to the national defense and military reform standards, and then saves this strategy in the form of a template for future use. By placing the processing template and the corresponding icon in the fixed path of the software, you can directly open and use it in the software interface according to the ordinary command, or you can call the template with a macro program. Flexible combination of processing templates or macro program parameters can effectively reduce the complexity of macro programs and facilitate changes

3. Generation of user menus. PowerMILL software provides a development environment in which users can define user menus by themselves. This menu is called user_ The text file of menu must be placed in the pmill2 directory of the user's home directory in the computer and saved in text format (not word file format), without a file name. The good macro programs are sorted reasonably in the user menu to produce the use environment of quick application macro programs. Click the right mouse button in the blank area of the PowerMILL tree viewer to call up this menu

4. Construction of machine tool library. First of all, the main structural parts of the machine tool to be simulated should be constructed according to the size in the modeling software. After the machine tool figure is decomposed according to the moving parts, it is saved separately to form * DMT (a graphic symbol file) format file. Then, considering the structural characteristics of the machine tool, determine the relative motion relationship and motion order of each moving axis of the machine tool, determine the motion range of each axis, the color of each moving part, etc., which are also defined by using a specific programming language format and a texter. I won't elaborate here

III. general process of programming with knowledge base

1 Preparation of processing program: using the basic parameter library of macro program, modify local parameters appropriately according to the actual processing needs, and prepare batch NC program, so that the program with large amount of data can be batch calculated at night

right click the blank area on the left side of the software interface to enter the user menu interface arranged by the user - common programming database. Enter different macro program parameter libraries according to the order of menus

1) call of digital analog machine tool. Select the machine tool library menu of the database, and the system will transfer all the machine tool head libraries of the company. Select the appropriate machine tool and reference coordinate system, and the machine tool in the processing preparation state can be displayed on the screen. With this digital machine tool, processing simulation and collision interference detection can be carried out

2) call of tool magazine. Select the tool library menu of the database, and the series of tools with tool holders commonly used in programming processing will be automatically generated in the system. Note that these tools correspond to the tool selection in the macro program one by one, so you must first transfer them into the tool library before using the macro program programming, and the name of the tool cannot be changed at will

transfer series tools from the tool library

3) use of macro programs. After transferring into the tool library, first select the machining coordinate system and confirm the reasonable machining blank, you can use the macro library to select the appropriate machining method and define the batch processing of the NC program. See Figure 10. 90% of the parameters of each macro program have been preset. Generally, the programmer only needs to follow the following steps:

use of macro program

4) use of contour macro program. The contour macro program is generated from rough machining to finish machining through an instruction according to the programming and processing habits of our company Ф 40 tool to Ф 4. Combined macro program of all contour programs such as tools. Compared with the previous programming methods, the programming efficiency is improved by more than 90% and the error rate of programming reasons is reduced by 100%. When using this macro program, you must pay attention to:

①. The reference line used must be the real theoretical contour of the part, and any gap, material thickness, etc. have been considered

②. The reference line used must be an open contour. For the closed contour, a gap of 0.01mm should be manually set at the starting point

③. Ensure that the direction of this line is the direction of processing forward milling

④. Temporarily change the name of the reference line used to "8888"

use of contour macro program

2 Sort out the details of the calculated program: re plan and partition the program. The partition principles: (1) use long and short knives for partition processing. (2) The steep area and flat area are processed separately. (3) Consider the feasibility of processing swing angle. (4) Different processing methods are adopted for the profile characteristics of different areas

3. Carefully check the rationality of the existence of the tool path, cut the empty tool path and useless tool path, filter the track that is too fine, and reduce the number of tool lifts. Macro parameters can be tried. When new products are developed again, they need to pass the "fine program cleaning" command in a series of performance test libraries

4. Cutting simulation of numerical control program: use cutting simulation tools to truly simulate the cutting process of blank materials, check the instantaneous cutting volume rate of blank materials, instantly reflect the amount of material cut by the tool, and optimize and change the machining path of the abnormally increased area

5. Dynamic simulation and Simulation of NC trajectory: quickly simulate the cutting process of the tool path, and check the rationality of the cutting direction and sequence of the tool path. It can also be transferred from the machine tool library to simulate the machine tool, truly reflect the motion process of the machine tool, and check whether there is motion interference between the machine tool and the workpiece

6. Rapid generation and transmission of NC programs and processing instructions

1) generation of NC programs

nc processing items should be saved in: (SX) mold drawing number part number and part name (i.e. processing item name). Note: if processing Foam solid mold, SX should be added before the mold drawing number to show the difference

use the function options of activating coordinate system output and programming coordinate system output in macro program, select the correct coordinate system output mode, and the system will automatically generate ncprograms folder, then all NC programs of the part will be automatically saved in (SX) mold drawing number part number and part name ncprograms

2) generation of processing instructions

before outputting the form, the NC program must check the interference and collision of the tool holder. The purpose is to: (1) check the rationality of the program partition. (2) By automatically extending the tool length, the detailed tool and tool holder information is listed in the manual (at present, it is only limited to the reference tool and tool holder information of the profile program)

program sheet: before generating the form, it is best to change the color of the model to gray for easy identification. Use the program form options in the macro program to fill in the file location After the mold drawing number and other contents, save the processing instruction in: (SX) mold drawing number part number and part name html (the name should preferably be fixed as HTML. First, you can use PowerMILL to open the processing items and forms at the same time, and second, it is convenient for unified management and consolidation. For program changes or the existence of multiple forms for a single project, you can add symbols to show differences, such as htmla, htmlb, etc.)

use the program form option in the macro program to automatically output the processing instructions, and add necessary auxiliary instructions, such as the description of the program swing angle limit, the direction of the cutter axis, the schematic diagram of the program partition, the ch hole, the hole position size of the imprint pin, etc

draw the schematic diagram of machining tool setting according to the programming zero point. The schematic diagram generally includes a plan view and a sectional view, which can fully express the coordinate position or tool setting dimension. Finally, insert the schematic diagram into the first page of the form - tool setting schematic diagram (i.e. html_ml file in HTML folder), replace the original graphics, and confirm to save

transfer of processing data. By establishing a large capacity NC project shared database, we can replace the NC program library currently used. When outputting, the NC project folder will be directly output. Each NC project as shown in Figure 3 will contain all processing information such as machining digital analog, tool path, NC program, tool setting instruction diagram, detailed program manual, etc. in this way, it is convenient to change the machining program, burn, weld, repair and other work in any connected computer (including the NC field). The hard disk capacity pressure of the computer used for reducing the process (the larger project folder is about 500m), It is convenient for centralized management and backup of programming data, and gradually realize the purpose of machine side programming

the following figure shows the typical structure of the programming project folder. Due to the limited capacity of the server at present, only the contents of shaded areas such as NC programs, program forms, machining schematics, tool path files, etc. are put into the server by copying and sorting out the original folders before transmission, and other contents such as machining digital analog, original data, etc. are not put into the server

use of project database

find the project folder in the server through the project path location indicated in the processing instruction. After opening the drawing number folder, you can see several folders named after the part name and part number, that is, the processing project folder. You can use PowerMILL software to open this processing project