Post processing technology II of the hottest NC ma

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Post processing technology of NC machining (2)

in engineering practice, when similar machining requirements of similar machining objects are met, the existing effective NC machining program can often be used after modification. However, how to ensure the correctness of the modified results is a problem. We can't put them all on the machine tool for debugging, which is particularly important in single piece processing. In addition, the machining simulation of many existing cad/cam systems is only based on the generated tool path file for machining simulation and interference inspection, which is obviously not enough. Therefore, the simulation (including logic simulation and process simulation) with NC code instruction set and its corresponding parameter settings as the information source is very important. Therefore, a perfect post processor should have the following functions:

1. Interface function: the post processor can automatically recognize and read the tool path files generated by different cad/cam software

2. NC program generation function: the NC machine tool has a series of functions except routine adjustment, such as linear interpolation, circular interpolation, automatic tool change, fixture offset, cooling, etc. the realization of the function is realized through a series of code combinations. The structure and sequence of the step code for fatigue life test of the front axle stand of the modern automobile are determined by the NC format specified by the NC machine tool. At present, some famous postprocessor companies in the world have developed a general postprocessor, which provides a functional database model. Users answer the questions raised by it according to the specific situation of CNC machine tools, and generate a special postprocessor for CNC machine tools designated by users through question answering. Users only need to have machine tool operation knowledge and NC programming knowledge, and they can program a satisfactory special post processor. When the database provided cannot meet the requirements of users, the developer provided by it allows users to modify and compile. Therefore, a relational database can be established according to the functions of the NC machine tool. How to realize each function is determined by the user according to the structure of the machine tool and the NC system used

3. Expert system function: the post processor can not only process and convert the tool path file, but also add some process knowledge. Such as the processing of high-speed machining, the selection of cutting parameters when machining lead screws, etc

4. Reverse simulation function: simulation with NC code instruction set and its corresponding parameter settings as the information source. It includes two parts:

check the main structure of NC program and check the syntax structure of NC program; NC machining process simulation. Based on the NC program, the machining process is simulated to judge the correctness of the motion trajectory and the rationality of the machining parameters. Load sensor force measurement

the structure and format of NC programs vary greatly with machine tools with different structures, different CNC systems, and different programming habits. Therefore, reverse simulation is very difficult. At present, there is no mature commercial software

to sum up, in order to directly apply the generated NC program to NC machine processing without manual modification, a special post processor must be customized for each NC machine. This requires developers to be familiar with the cam system used and the format of the generated tool path file, as well as the NC machine tool used and its NC system code function and its expression format. This work is an intelligence intensive and labor-intensive process. When faced with many CAM systems and many machine tools and CNC systems, the work of developing a special post processor from scratch is quite heavy. Therefore, in recent years, there has been a practice of customizing the special post processor for NC machine tools based on the development of general post processor and the application of NC code oriented and other related technologies. The general post processor is used to solve common problems, and the customized post processor is used to solve individual problems. Practice shows that this is an effective method. Applying this method, the Institute has successively developed and customized ten special post processors for various types of machine tools, including gantry five sided machining center, gantry vertical machining center, horizontal flexible machining unit, vertical machining center, CNC lathe, turning center, etc. since 1996. The CNC system includes FANUC, tosnuc, Mitsubishi, A2100, a850, Mazak, etc., covering the products and CNC equipment used by the Institute, It has achieved good results in engineering application. Among them, for the development of the special post processor of the horizontal machining center with three-axis rotary table and the five face machining center, the post-processing structure model of this kind of structure machine tool is established, and the development experience is accumulated

the following is a brief introduction of the method of using the general post processor to customize and develop the special post processor for hc800/fanuc-15ma:

ncpost module of the customized development software pro/e used by the hospital. This module is an ICAM general post-processing developer produced by Canadian ICAM technology company

cam module of CAM software pro/e used. The cam module of pro/e is applied to design the machining environment, simulate the machining, and generate the tool path file

nc program application object horizontal machining center hc800. The machine tool is manufactured by Hitachi Precision Machinery Co., Ltd. in Japan. It is equipped with three linear axes' x ',' y 'and' Z ', a rotary workbench, a chain tool magazine with a capacity of 120 knives, and six exchange pallets; The control system is fanuc-15ma, which is mainly used for the processing of box parts

first, understand the structure of the machine tool, the auxiliary equipment equipped with the machine tool, the functions of the machine tool and the way to realize the functions (manual or automatic)

be familiar with the NC programming of the NC system equipped with the machine tool, including the composition and meaning of the function code, and whether there is a code format different from ISO standard

apply the general post processor oriented template, answer the questions raised by the template one by one according to the above knowledge, and customize the special post processor. The general post processor calls its internal database model according to the external input information, and generates the special post processor required by the user after judgment, arrangement and combination

the hc800/fanuc-15ma special post processor customized according to this method is used to process the tool path file. About 80% of the generated NC program is available, and 20% needs further development

when the data model provided by the general post processor cannot meet the requirements of users, or users need to optimize the processing of NC programs, the database model shall be modified by the application development software. This requires developers to master the use of cam module, master the format of tool path file, and have experience in software development and processing technology

the machine tool used in this special post processor is a three-axis horizontal machining center equipped with a rotary workbench, and the workbench rotation cannot participate in the cutting movement. Machine tool

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